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UNIVERSITY  OF  ILLINOIS, 

Agricultural  Experiment  Station, 

CHAMPAIGN,  DECEMBER,  189?. 


BULLETIN  NO.  29. 


CONTENTS — ORANGE  RUST  IN  RASPBERRIES  AND  BLACKBERRIES. 
A  NEW  FACTOR  IN  SCIENTIFIC  AGRICULTURE. 


*ORANGE  RUST  OF  RASPBERRY  AND  BLACKBERRY. 

For  the  past  twenty-five  years  notes  have  appeared  in  various  agri- 
cultural and  horticultural  publications  of  this  country  of  a  fungus  occur- 
ring on  raspberries  and  blackberries,  which,  on  account  of  the  bright 
orange  colored  spores  produced  on  the  leaves,  has  been  uniformly  known 
as  "  orange  rust."  So  marked  and  so  persistent  is  the  action  upon  these 
berry  plants,  its  "hosts,  "  of  this  lowly  organized  parasitic  plant  that  it  is 
recognized  as  one  of  the  most  destructive  of  what  are  known  as  parasitic 
fungi. 

To  botanists  this  fungus  has  been  known  since  the  earlier  part  of 
the  present  century,  when  it  was  first  mentioned  as  occurring  in  Kam- 
tchatka,  and  soon  after,  in  Carolina  of  this  country.  A  glance  at  "Distri- 
bution "  in  the  Appendix  shows  that  it  is  quite  widely  spread  over  the 
eastern  part  of  the  United  States.  In  some  localities,  however,  it  is 
much  more  abundant  than  in  others.  Mention  of  it  has  not  been  found  as 
occurring  further  west  than  Nebraska,  and  Dr.  Harkness,  in  a  letter, 


*The  writer  wishes  to  acknowledge  his  indebtedness  to  Professor  Burrill,  who 
first  suggested  the  possible  relationship  of  Caeoma  nitens  and  Puccinia  Peckiana,  and  at 
whose  suggestion  the  investigation  of  their  life  histories  was  undertaken.  To  various 
botanists  who  have  responded  to  our  letters  of  inquiry,  thanks  are  also  due.  Refer- 
ence to  articles  is  made  in  the  text  by  giving  author's  name  and  date  of  pub- 
lication; but  such  references  may  be  found  more  fully  given  under  "  Literature,"  in 
the  Appendix.  After  the  above  paper  had  been  written  for  publication,  an  arti- 
cle by  Tranzschel,  published  in  Hedwigia,  was  received.  By  artificial  infection,  this 
writer  so  completely  verifies  the  results  that  we  have  obtained  that  his  experiments 
have  been  added  to  the  paper,  and  proper  credit  has  been  given. 

273 


274  BULLETIN  NO.  29.  [  December, 

states  that  he  has  never  collected  it  in  California.  It  is  not  at  all  im- 
probable, however,  that  it  may  be  found  further  west.  Reports  give  it 
as  occurring  in  our  most  southern  states,  and  from  them  it  extends  be- 
yond our  northern  limits  into  Canada.  In  Europe  and  Asia,  while  not 
so  numerously  reported,  it  has  been  found  over  a  large  range  of  territory 
and  is  said  to  be  quite  common  in  some  of  the  northern  stations. 

So  far  as  known  this  fungus  has  limited  its  ravages  to  the  genus 
Rubus.  Both  cultivated  and  wild  species  are  freely  attacked,  and  of  the 
former  quite  a  number  of  varieties  have  been  reported  as  more  or  less 
injured,  of  which  the  Kittatinny  is  perhaps  one  of  the  worst  affected. 
In  this  region  the  Snyder  seems  usually  to  be  quite  exempt  from  at- 
tack, although  elsewhere  reported  as  more  or  less  infected.  In 
the  Appendix  is  given  a  list  of  species  so  far  found  to  be  attacked. 

The  fungus  shows  its  first  signs  of  appearance  in  early  spring, 
varying  slightly  in  time  as  the  weather  is  favorable  or  not  to  the  growth 
of  its  host.  In  this  locality  it  can  first  be  detected  during  the  latter  part 
of  April  or  the  first  of  May.  As  soon  as  the  leaves  are  fairly  started  in 
their  development,  and  before  they  are  unfolded,  what  is  known  as  the 
spermagonial  stage  can  be  seen.  The  spermagonia  resemble  small 
stalked  glands  thickly  covering  both  sides  of  the  leaf,  and  at  first  are  so 
deceiving  in  their  appearance  as  to  be  mistaken  for  glands  naturally  be- 
longing to  the  leaf.  As  the  leaves  mature,  the  spermagonia  become 
more  distinct,  and  while  usually  found  covering  the  leaves  of  the  affected 
plant,  are  sometimes  variously  limited  in  their  distribution.  Some  leaves, 
usually  the  upper,  may  be  affected,  and  others  entirely  free;  even  some 
of  the  leaflets  of  a  single  leaf  may  show  this  stage  while  others  do  not. 
Nor  is  it  an  uncommon  occurrence  to  find  definitely  affected  patches  of 
an  individual  leaflet  sharply  marked  off  from  the  remaining  apparently 
healthy  parts.  About  two  or  three  weeks  after  the  first  appearance  of 
the  spermagonia,  the  second,  or  aecidium  stage  becomes  noticeable, 
showing  as  concealed,  slightly  elevated  spots  thickly  covering  the  under 
surface  of  the  leaf.  The  rapid  growth  of  these  soon  ruptures  the  epi- 
dermis above  each  bed  of  spores,  and  they  then  show  as  bright  orange 
colored  masses.  About  this  time  the  spermagonia  have  reached  their 
maximum  development.  So  far  as  observed  the  aecidium  stage  is  lim- 
ited to  those  leaves  or  parts  of  the  leaf  that  were  affected  by  the  sperma- 
gonia, although  all  parts  affected  with  spermagonia  do  not  necessarily 
produce  the  former.  The  aecidium  stage  is  confined  almost  entirely  to 
the  lower  surface  of  the  leaf,  rarely  slightly  affecting  the  margin  on 
the  upper  side.  It  is  also  found,  in  rare  cases,  on  the  stems.  It  reaches 
its  maximum  development  here  during  the  first  part  of  June,  and  during 
the  latter  part  of  the  month  gradually  disappears  until  only  isolated 
cases  can  rarely  be  found  during  the  first  of  July.  Some  writers  men- 
tion it  as  occurring  again  during  the  autumn  months.  Brunk  (1890) 
claims  to  have  found  it  in  Maryland  as  late  as  the  middle  of  October, 
and  writes  that  in  the  extreme  southern  states  he  has  found  specimens  in 


1893- J        ORANGE   RUST  IN   RASPBERRIES   AND  BLACKBERRIES.  275 

December.     It  has  been  found  by  the  writer  during  the  spring  and  early 
summer  only. 

The  fungus  is  found  on  the  leaves  of  old  and  new  shoots,  and  is 
usually  so  vigorous  in  its  spore  development  that  it  utterly  destroys  the 
usefulness  of  the  affected  leaves.  These  fall  off  in  time,  and  if  the 
fungus  has  not  so  far  impaired  the  vitality  of  the  plant  as  to  prevent 
further  development,  the  subsequent  growth  of  branches  with  unaffected 
leaves  may  help  repair  the  damage.  Frequently,  however,  especially  in 
young  shoots,  the  canes,  stripped  of  their  leaves,  hindered  in  growth, 
fail  to  overcome  the  damage,  and  so  die.  Since  it  is  also  a  fact  that  a 
plant  once  infected  is  quite  certain  of  attack  each  succeeding  year,  it  is 
usually  only  a  matter  of  time  before  the  most  vigorous  of  plants  are 
rendered  worthless.  Sometimes  the  presence  of  only  the  spermagonial 
stage  is  sufficient  seriously  to  affect  the  efficiency  of  young  shoots. 
Horticultural  papers  sometimes  contain  notices  of  localities  in  which 
blackberries  and  raspberries  in  general  are  so  seriously  affected  by  this 
disease  as  to  render  their  cultivation  unprofitable,  if  not  impossible. 
The  same  plants  or  patches  being  annually  subject  to  attack  early  led 
many  to  suppose  that  the  fungus  must  be  perennial  in  its  host,  a  fact 
which  was  first  publicly  demonstrated  by  Newcombe  (1891),  who 
found  mycelium  in  microscopical  sections  taken  from  different  parts  of 
affected  plants. 

This  perennial  nature  of  the  fungus  makes  successful  prevention  of 
the  disease  exceedingly  difficult.  Various  methods  of  treatment  have 
been  made,  of  which  probably  only  one  has  given  any  uniformly  good 
results,  that  of  digging  up  and  destroying  all  affected  plants  as  soon  as 
signs  of  disease  were  manifested.  Spraying  has  been  tried  to  see  if  any 
good  could  be  accomplished.  With  the  mycelium  perennial  in  the  host, 
the  good  in  this  case  must  be  in  preventing  the  spread  of  the  disease  to 
unaffected  plants,  and  then  only  under  conditions  depending  upon  the 
life  history  of  the  fungus.  If  the  aecidiospores  germinate  upon  the 
leaves  of  Rubus  to  produce  another  stage  of  development,  then  spray- 
ing at  the  proper  season  should  be  beneficial  in  this  direction.  As  the 
indications  are  that  the  above  supposition  is  correct,  spraying  with  Bor- 
deaux mixture  as  soon  as  the  aecidiospores  begin  to  show,  preceded 
by  a  thorough  cutting  out  of  plants  as  soon  as  signs  of  the  disease  are 
manifested,  should,  in  a  few  seasons,  eradicate  this  disease.  As  the 
spores  in  germination  seem  to  gain  entrance  on  the  under  side  of  the 
leaf,  it  would  be  especially  necessary  in  spraying  to  wet  that  side.  The 
fungus  has  also  some  natural  enemies  that  are  of  slight  use  in  destroying 
its  spores.  Among  these  may  be  mentioned  the  larvae  of  certain  insects, 
which  feed  quite  greedily  on  the  spores,  and  Tuberculina  persicina,  a 
fungus  which  occurs  frequently  as  a  parasite  on  the  sori. 

Having  stated  that  a  plant  once  attacked  by  this  disease  is  perennially 
subject  to  it,  let  us  see  why  this  is  so.  This  will  lead  us  to  consider  the 


276  BULLETIN  NO.  29.  [December, 

vegetative  stage  of  the  fungus,  or  what  is  technically  known  as  the 
mycelium. 

MYCELIUM. 

The  bright,  orange  colored  patches  on  the  under  side  of  the  leaves 
are  made  up  entirely  of  spores,  or  the  reproductive  part  of  the  fungus. 
To  produce  these  there  must  be  a  vegetative  system ;  just  as  to  produce 
the  fruit  of  the  blackberry  there  must  be  the  root,  the  stem,  and  the  leaf. 
This  vegetative,  or  mycelial  stage  is  concealed  entirely  within  the  plant, 
and  in  this  fungus,  contrary  to  the  usual  rule  of  its  family,  is  quite 
extensively  developed.  To  show  this,  microscopical  sections  of  the 
affected  plants  are  necessary.  From  those  made  of  variously  affected  parts 
the  following  facts  have  been  learned  concerning  this  stage  of  the 
fungus:  Such  sections  reveal  mycelial  threads  present  from  the  upper 
parts  of  the  roots  running  through  the  stem  up  into  the  uppermost 
leaves  showing  signs  of  affection.  That  is,  we  may  take  any  affected 
leaf,  make  sections  of  its  blade,  its  petiole,  the  junction  of  petiole  to 
branch  or  main  shoot,  and  so  down  the  stem  to  the  perennial  part,  and 
«ven  somewhat  into  the  root  itself,  and  in  all  the  sections  find  the  my- 
celium. Frequently  plants  are  found  in  which  the  new  shoots  are 
affected  but  the  old  ones  ar,e  free.  In  such  cases  the  mycelium  is  found 
in  the  former  only.  The  canes  of  raspberries  and  blackberries  are  bi- 
ennial, and,  so  far  as  personal  inspection  goes,  unless  these  are  infected 
during  their  first  year  they  can  not  be  the  second ;  and  if  they  are 
affected  the  first  year,  they  are  quite  sure  to  be  the  next.  This  is  easily 
explained  by  the  fact  that  the  mycelium  follows  young  growing  cells, 
and  cannot  penetrate  tissue  to  any  extent  after  it  has  matured.  Sections 
of  very  young  canes  of  the  diseased  plants  show  that  they  contain  my- 
celium, and  that  in  such  it  follows  quite  closely  the  point  of  growth.  In 
such  sections,  fungus  threads  have  been  traced  from  the  stem  into  the 
scale-like  leaves  protecting  it,  and  into  the  ordinary  leaves  before  they 
have  become  differentiated  into  blade  and  petiole.  Sections  of  roots, 
except  in  the  neighborhood  of  the  merging  of  root  and  stem,  do  not 
show  the  mycelium.  Now,  from  the  above,  one  can  see  how  a  single 
plant  can  have  both  new  and  old  stems  affected  and  free,  illustrations  of 
which  are  sometimes  met.  In  such  a  case  the  unaffected  canes  come 
from  underground  parts  into  which  the  mycelium  failed  to  pene- 
trate when  they  were  young,  and  so  was  shut  out;  and  the  affected  ones 
come  from  where  the  mycelium  had  gained  entrance.  The  above  facts 
also  prove  that  the  first  infection  of  a  plant  must  be  through  the  shoots 
when  very  young  and  easy  of  penetration.  The  plants  present  this 
condition  during  late  fall  and  early  spring.  As  illustrating  the  perennial 
nature  of  the  fungus,  and  method  of  infection,  the  following 
experiment  is  given:  In  1892  eighteen  plants  were  marked,  of  which 
ten  were  affected  with  this  Caeoma  and  eight  were  free.  In  1893  these 
were  examined  again,  and  the  ten  diseased  in  1892  were  found  to  be  in 


1893']        ORANGE   RUST  IN  RASPBERRIES  AND  BLACKBERRIES.  277 

the  same  condition,  and  the  eight  healthy  ones  of  the  year  before  were 
so  still,  except  in  one  case.  This  plant  was  affected  only  on  the  new, 
very  young  canes,  showing  that  through  them  the  fungus  gained 
entrance. 

The  structure  of  this  vegetative  stage,  when  examined,  is  found  to 
consist  of  two  parts — mycelial  threads  and  haustoria.  The  function  of 
the  former  is,  evidently,  to  carry  the  fungus  to  different  parts  of  the 
plant;  and  so  the  threads  are  found  between  the  cell  walls,  quite  often 
in  the  spaces  where  three  or  more  cells  come  together.  In  transverse 
sections  of  the  plant  these  show  as  cut  ends,  while  in  longitudinal  sec- 
tions they  can  frequently  be  traced  for  quite  a  distance.  In  such  cases 
they  appear  as  hyaline  filaments  of  varying  diameter,  having  definite 
cell  walls,  and,  according  to  age,  more  or  less  protoplasm.  From  these 
spring  the  haustoria,  similar  but  very  short  threads.  The  haustorium 
pierces  the  cell  wall  by  a  narrow  neck  and  inside  the  cell  enlarges  into 
a  body  with  a  more  or  less  knobbed  end,  the  function  of  an  haustorium 
being  to  supply  nourishment  necessary  for  the  growth  of  the  mycelium. 
The  fungus  filaments  are  not  found  distributed  irregularly  through  the 
plant,  but  are  limited  to  certain  localities.  In  the  root  and  root-like  part 
they  are  found  between  the  parenchyma  cells  of  the  cortex  in  the  vicinity 
of  the  cambium.  The  abundance  of  starch  in  these  cells  makes  it  neces- 
sary that  very  thin  sections  be  made,  which  show  best  when  stained  with 
an  alcoholic  solution  of  potassium  iodide  and  iodine,  thereby  coloring  the 
starch  grains  blue  and  the  fungus  a  yellowish  green.  In  cells  contain- 
ing haustoria  their  effect  upon  the  amount  of  starch  in  very  evident 
{Plate  j>,  fig.  12).  As  a  rule,  in  this  part  of  the  plant,  the  largest  and 
most  knobbed  of  the  haustoria  have  been  found.  In  the  stems  the  my- 
celium is  found  in  the  pith,  mostly  between  the  smaller  cells  near  the 
fibre-vascular  bundles.  The  leaves  have  the  mycelium  entering  them 
when  quite  young,  and  the  interstices  of  the  parenchyma  cells  afford  its 
abode.  In  young  shoots  the  mycelium  is  not  so  limited  to  particular 
localities,  occurring  occasionally  among  the  parenchyma  cells  of  the 
bark,  and  even  among  the  outermost  cells  of  the  bundles  not  yet  fully 
developed. 

The  appearance  of  the  mycelium  depends  somewhat  on  its  age. 
When  young  it  is  more  conspicuous,  but  when  old  it  loses  its  proto- 
plasm and  acquires  an  occasional  septum.  The  haustoria  are  at  first 
simple  threads  extending  half  way  or  more  across  the  cell.  They  soon 
begin,  by  coiling  or  wisting,  to  form  an  enlarged,  knotted  end.  This 
possibly  may  be  due  to  the  effort  of  the  haustorium  to  come  into  more 
intimate  contact  with  its  food  particles.  Sometimes  two  haustoria  are 
found  in  the  same  cell,  and  not  infrequently  have  there  been  seen  signs 
of  union  of  these  {Plate  j,  fig.  j>,  ^,  7).  This,  however,  is  to  be 
interpreted  as  nothing  more  than  an  accidental  occurrence. 

Late  in  April  a  more  conspicuous  gathering  of  mycelium  in  special 
places  just  beneath  the  epidermis  of  the  leaves  is  noticeable,  and  then 


278  BULLETIN  NO.  29.  [December, 

begins  the   formation  of  the  first  fruiting  stage  of  the   fungus,  or  the 
spermagonia. 

SPERMAGONIA. 

Transverse  sections  through  one  of  these  mycelial  groups  at  this 
time  show  the  threads  as  an  indefinite  mass  chiefly  in  cross  section.  The 
threads  begin  to  grow  upward  between  the  lateral  union  of  contiguous 
epidermal  cells,  forcing  the  cells  apart  and  upward  as  a  slight  papilla. 
Sections  now  show  the  mycelium  in  these  papillae  more  in  longitudinal 
view  as  closely  packed,  septate  threads,  and  the  epidermis  above  the 
infected  spot  is  seen  as  two  large  cells,  forced  above  the  level  of  the  sur- 
rounding cells  at  their  juncture  with  each  other,  and  separated  from  each 
other  at  their  bases  by  the  intervening  mass  of  mycelium  {Plate  2,  fig. 
J,  2).  According  to  Richards  (  1893)  further  growth  so  pushes  against 
the  interior  walls  of  these  elevated  cells  as  to  cause  them  to  collapse, 
and  the  cells  become  filled  with  mycelium.  The  upright  threads,  so 
closely  crowded  together  as  to  form  a  sort  of  false  tissue,  having 
reached  their  growth,  begin  to  cut  off  from  their  upper  free  ends  numer- 
ous small  oval  bodies.  These  are  known  as  spermatia,  and  when 
entirely  formed  occupy  about  the  upper  third  of  the  spermagonium. 
When  they  have  been  formed  in  sufficient  numbers,  the  epidermal 
covering  becomes  punctured,  and  they  ooze  out  on  the  exterior  of  the 
leaf  as  a  small  viscid  drop. 

The  function  of  these  spore-like  bodies  is  not  definitely  known. 
Some  botanists  consider  such  as  male  elements  concerned  in  the  fertiliza- 
tion of  the  aecidium  stage  of  fungi.  The  function  of  somewhat 
similar  bodies  found  in  lichens  has  led  to  this  view,  and,  while  rather 
generally  accepted,  there  seems  to  be  no  direct  evidence  that  these  so- 
called  spermatia  are  really  such.  Some  have  thought  that  these  bodies 
effect  fertilization  of  the  mycelium,  while  others  have  held  that  each 
aecidiospore  may  be  fertilized  by  a  spermatium,  as  spermatia  are  fre- 
quently seen  adhering  to-the  spores.  The  fact  that  spermagonia  are  gen- 
erally produced  with  the  aecidium  stage,  and  that  both  are  borne  on  the 
same  mycelium  suggests,  at  least,  intimate  relationship.  Other  botanists 
have  discarded  the  idea  that  these  were  at  all  sexual  elements,  and  declare 
that  they  are  merely  conidial  stages  of  the  fungus,  and  that  the  so-called 
spermatia  are  conidiospores.  Plowright,  holding  this  view,  claims  to 
have  produced  a  yeast-like  germination  of  these  bodies  in  sweetened 
water.  A  similar  germination  was  also  previously  claimed  by  Cornu. 
In  culture  experiments  with  the  spermatia  of  this  fungus,  such  a  method 
of  reproduction  has  been  noticed,  but  satisfaction  was  not  had  that  such 
did  not  contain  yeast  fungi.  The  chief  objection  to  the  view  that  these 
are  conidial  bodies  is  the  special  use  they  could  have,  since  they  are  gen- 
erally produced  in  connection  with  the  aecidium  stage  whose  spores 
have  an  almost  similar  function.  Winter  merely  says  that  the  physi- 
ological significance  of  the  spermatia  is  not  yet  surely  made  out.  Be 


1893-]     '  ORANGE   RUST  IN   RASPBERRIES   AND   BLACKBERRIES.  279 

their  use  what  it  may,  about  the  time  of  their  maximum  development 
the  signs  of  a  second  spore  stage  become  visible  to  the  naked  eye. 

CAEOMA,  OR  AECIDIUM  STAGE. 

This,  known  as  "orange  rust,"  is  the  most  conspicuous  stage,  on 
account  of  being  seen  externally  and  because  of  the  bright  color  of  the 
spores.  Like  the  spermagonia,  it  has  its  origin  in  the  mycelium  of  the 
leaf,  only  this  time  the  mycelium  begins  to  form  in  masses  on  the  lower 
side  of  the  leaf.  Here  is  produced  a  more  extended  development  of 
filaments.  From  these  arises  a  compact  mass  of  threads  divided  with 
septa,  in  a  basipetal  manner,  into  distinct  cells.  The  distal  cells  gradually 
become  rounded  at  their  septal  unions,  and  are  less  securely  fastened 
together.  Their  walls  also  become  minutely  verruculose,  and,  though 
hyaline,  are  given  an  apparent  color  by  the  endochrome  which  with  the 
protoplasm  fills  the  cell.  The  aecidiospores  thus  mature,  and  separate 
into  distinct  bodies.  These  being  formed  now  just  beneath  the  epidermis, 
the  strain  on  it  becomes  too  great  and  a  rupture  takes  place.  The 
epidermis  above  the  sorus  soon  wears  away  and  the  golden  spot,  until 
now  seen  indefinitely  through  the  epidermis,  shows  as  bright  orange. 
The  spores  when  fully  matured  vary  from  elliptical  or  oblong  to  sub- 
globose,  and  usually  measure  12  to  24  by  18  to  32  microns.  Their  thin, 
hyaline  exospore  is  finely  covered  with  minute  tubercules.  Their  orange 
color  is  due  to  the  presence  of  a  considerable  amount  of  endochrome. 

If,  soon  after  these  spores  are  mature,  they  are  put  in  a  moist  place 
germination  takes  place.  In  watching  this  under  the  microscope,  the  fol- 
lowing has  been  found  most  useful:  A  glass  ring,  the  diameter  of  the 
cover  glass  and  about  a  quarter  of  an  inch  high,  is  fastened  to  the  glass 
slip  by  means  of  vaseline.  In  a  drop  of  sterilized  water  on  the  cover  glass 
are  dusted  a  few  of  the  mature  spores.  This  is  inverted  and  fastened 
on  the  top  of  the  ring  by  means  of  vaseline  previously  placed  on  its 
edges.  If  for  any  reason  one  finds  the  water  drop  too  deep  for  focusing 
on  its  free  surface,  this  can  be  prevented  by  washing  the  cover  before 
use  with  caustic  potash.  Cultures  thus  made  can  be  examined  through 
all  stages  of  spore  germination  without  fear  of  evaporation.  Mature, 
fresh  spores  often  show  signs  of  germination  within  three  hours  after 
being  placed  in  water.  The  first  sign  is  a  small  swelling  appearing  on 
the  side  of  the  spore.  The  contents  of  the  spore,  surrounded  by  the 
endospore,  have  pierced  the  exospore  through  a  small  opening,  and 
have  swollen  into  a  small  hyaline  body.  This  gradually  lengthens  by 
apical  growth  into  filamentous  form,  and  then  the  endochrome  appears 
in  the  tube  as  small  colored  globules.  The  growth  of  the  tube  is  about 
the  same  for  eight  or  ten  hours,  when  it  has  reached  a  length  three  or 
four  times  the  diameter  of  the  spore.  All  this  time  the  protoplasm  has 
been  disappearing  from  the  spore  and  entering  the  germ  tube.  The 
protoplasm  of  the  spore  at  first  becomes  less  dense,  then  vacuoles  appear, 
and  the  contents  are  gradually  limited  to  the  region  of  the  germ  pore. 


280  BULLETIN  NO.  29.  [December, 

The  spore  is  thus  emptied  in  about  eight  hours,  but  the  germ  tube  keeps 
on  growing,  and  gradually  becomes  empty  at  its  base.  As  the  proto- 
plasm recedes  from  the  lower  part  of  the  tube,  an  occasional  septum 
may  be  formed.  Growth  is  practically  stopped  only  by  the  exhaustion 
of  the  protoplasm,  and  usually  lasts  for  two  or  three  days  after  the  first 
signs  of  germination,  the  length  of  the  tubes  at  this  period  frequently 
being  eight  or  more  times  the  diameter  of  the  spore.  The  germ  tubes 
are  mostly  of  a  uniform  diameter,  with  the  tips  sometimes  slightly  nar- 
rowed. They  usually  present  a  slightly  flexuous,  rather  than  a  rigid, 
straight  growth.  Upon  some  occasions  movement  of  the  protoplasmic 
granules  can  be  seen  in  the  germ  tubes.  Occasionally  germination  pre- 
sents anomalies  in  the  shape  of  suddenly  enlarged  or  of  flexuous  tips, 
and  in  a  single  case  branching  has  been  seen,  but  never  more  than  a 
single  developed  germ  tube  has  been  found  to  a  spore. 

Such  being  the  characters  presented  in  artificial  germination,  in  what 
manner  should  we  expect  these  spores  to  act  when  infecting  their  hosts? 
Botanists  have  proved  that  such  summer  spores  gain  entrance  into 
plants  by  the  growth  of  the  germ  tubes  into  the  stomates  of  the  epider- 
mis and  so  into  the  parenchyma  tissue  of  the  leaves.  This  being  the  case 
it  is  left  for  decision  whether  with  these  germinating  spores  the  black- 
berry and  raspberry  leaves  are  used  for  further  development,  or  whether, 
as  i*  so  often  the  case,  some  other  entirely  different  plants  have  been 
chosen.  The  indications  being  that  the  former  was  the  case,  artificial 
growth  on  the  leaves  was  undertaken.  In  both  raspberry  and  black- 
berry, the  stomates  are  almost  entirely  confined  to  the  under  side  of  the 
leaf,  some  few  being  found  on  the  margins  of  the  upper  side.  In  the 
former,  too,  the  lower  surface  is  so  covered  by  hairs  as  to  afford  consid- 
erable difficulty  in  examining  the  epidermis.  So  blackberry  leaves  on  a 
small  shoot  were  moistened  on  their  lower  surface  and  then  dusted 
with  spores.  The  shoot  was  then  placed  in  a  moist  chamber  and  left 
for  twenty-four  hours.  Examination  of  the  leaves  was  then  made  under 
the  microscope.  The  epidermis  of  these  leaves  sticks  so  closely  to  the 
parenchyma  cells  that  it  cannot  be  satisfactorily  removed.  The  leaf 
itself  is  too  opaque  for  examination  under  high  powers.  It  was  neces- 
sary, therefore,  carefully  to  soak  pieces  of  the  leaf  in  hot  caustic  potash, 
wash,  and  squeeze  slightly  under  the  cover  glass  before  the  surface  of 
the  epidermis  could  be  examined.  Such  a  process,  however,  is  likely 
to  wash  off  any  spores  that  may  be  on  the  surface  of  the  leaf.  Under  such 
circumstances  were  found,  on  one  occasion,  spores  that  showed  signs  of 
entering  the  stomates  {Plate  4,  Jig.  22).  These  spores  presented  char- 
acters never  seen  in  mere  water  cultures;  for,  after  they  had  sent  out  an 
ordinary  tube  about  three  times  the  diameter  of  the  spore,  it  suddenly 
became  considerably  narrowed ;  and  in  several  cases  this  narrowed  part 
was  found  between  the  guard  cells  of  the  stomates,  showing,  at  least, 
that  the  fungus  could  gain  entrance  in  this  way.  No  germ  tubes  were 
ever  found  piercing  through  the  epidermis  itself.  The  experiment  of 


1893-]        ORANGE   RUST  IN   RASPBERRIES  AND  BLACKBERRIES.  28l 

inoculating  a  healthy  plant,  kept  indoors,  was  also  tried ;  but  as  about 
the  time  results  from  this  could  be  expected  the  plant  died,  evidence  in 
either  direction  was  wanting. 

Since  these  spores  germinate  readily  as  soon  as  mature,  and  prob- 
ably infect  blackberries  and  raspberries  through  their  leaves,  it  might 
seem  that  they  were  means  of  spreading  the  aecidium  stage  from  plant 
to  plant.  But  when  we  consider  that  this  stage  is  limited  to  spring  and 
that  no  plant  or  parts  of  a  plant  become  diseased  except  those  early 
showing  its  signs,  such  an  inference  becomes  impossible,  and  we  are  led 
to  inquire  to  what  does  this  stage  give  rise?  This  brings  to  our  consid- 
eration what  is  known  as  alternation  of  spore  forms. 

ALTERNATION  OF  SPORE  FORMS. 

The  fact  that  the  aecidiospores  soon  lose  their  power  of  germina- 
tion, coupled  with  the  knowledge  that  such  spores  have  been  proved  in 
numerous  cases  to  be  merely  summer  stages  of  more  advanced  forms, 
has  suggested,  with  almost  certainty,  that  this  fungus  has  other  spore 
stages  in  its  life  history  not  now  recognized  as  belonging  to  it.  Botanists 
have,  therefore,  suggested  different  forms  as  the  mature  stage,  basing 
their  opinions  on  more  or  less  superficial  observations.  Let  us  see  what 
evidence  there  is  that  such  are  advanced  stages  of  this  fungus. 

Melampsora.  Dietel  gives  the  following  species  of  Melampsora  and 
Caeoma  that  different  investigators  have  connected  with  each  other  by 
culture  experiments. 
Melampsora  Salicis  capreae,  (Pers.)  and  Caeoma  Euonymi,  (Gmel.) 

— Rostrup. 

Melampsora  Hartigii,  (Thiim.)  and  Caeoma  Ribesii,  Lk. —  Rostrup. 
Melampsora  aecidioides,  (DC.)  and  Caeoma  Mercurialis,  (Pers.) 

— Plowright. 

,,  ,  rr,  ,     (  Caeoma   Mercurialis*  (Pers.)       ) 

Melampsora  Tremulae,  Tul.  and    \  ^  *•    •*  ADT 

(  Caeoma  pimtorquum,     A.    Br.    \ 

— Rostrup. 

Melampsora  Tremulae,  Tul.  and  Caeoma  Laricis,  (Westd.) — Hartig. 
Melampsora  Populina,  Jacq.  and  Caeoma  Laricis,  (Westd.) — Hartig. 
Plowright  also  made  cultures  to  duplicate  the  above  results,  but  was 
successful  in  only  the  case  attributed  to  him.  These  results  indicate  a 
close  relationship  between  Melampsora  and  Caeoma,  and  suggest  that 
the  mature  form  of  the  Caeoma  we  are  considering  might  be  found 
among  the  species  of  Melampsora.  So  far  as  is  known  no  culture  ex- 
periments have  been  made  along  this  line.  The  fact  that  this  Caeoma 
is  so  common  would  indicate  that  the  teleutoform  was  not  rare,  and  this 
again  would  suggest  the  Melampsora  on  Populus  or  Salix  as 
the  most  probable  one;  but,  apparently,  the  above  investigators  have 
found  both  of  these  species  connected  with  entirely  different  species  of 
Caeoma.  Rathay  also  claims  to  have  found  Melampsora  populina  as 
connected  with  Aecidium  clematidis,  and  this,  taken  with  other  conflict- 


282  BULLETIN  NO.  29.        .  [December, 

ing  results  in  the  above  list,  makes  it  quite  improbable  that  all  species  of 
Caeoma  will  be  found  connected  with  Melampsora  as  the  mature  stage. 

Phragmidium.  Another  genus  with  which  some  botanists  have 
suggested  connection  with  this  Caeoma  is  Phragmidium,  especially  with 
the  species  Ph.  Rubi.  The  facts  that  in  this  genus  all  three  spore  forms 
may  occur  on  the  same  host  species,  and  that  in  some,  Ph.  mucronatum, 
the  aecidium  stage  has  gross  resemblance  to  C.  nitens,  together  with  the 
further  facts  that  Ph.  Rubi  and  C.  nitens  are  found  on  the  same  hosts 
and  frequently  in  the  same  localities,  seem  to  be  the  chief  points  in 
favor  of  considering  them  as  forms  of  the  same  thing.  Perhaps,  too, 
the  fact  that  the  aecidium  form  of  Ph.  Rubi  is  wanting  or  little  known 
in  some  localities  has  had  much  to  do  with  suggesting  the  connection. 
These,  however,  are  too  general  points  to  be  of  definite  value  in  proving 
connection  of  the  forms.  Let  us  see  what  more  specific  points  will 
indicate.  As  to  structure,  we  find  some  difference  between  the 
ordinary  aecidium  stage  of  Phragmidium  and  this  Caeoma,  for  in  the 
former  paraphyses  surrounding  the  sori  are  characteristic,  while  in  the 
latter  there  is  no  evidence  of  them.  We  find  no  recorded  cases  of  both 
forms  occurring  commonly  on  the  same  individual  host,  as  one  might 
expect  if  they  were  related.  Then,  in  this  locality  at  least,  the  failure 
to  find  this  Caeoma  after  the  first  of  July,  while  the  collections  of  Ph. 
Rubi  have  not  been  made  earlier  than  September,  is  also  against  their 
connection,  as  two  months  between  the  disappearance  of  an  aecidium  and 
the  appearance  of  an  uredo  form  is  too  long  a  time  for  which  to  account. 
Lastly,  most  European  botanists  have  considered  this  Caeoma  as  distinct 
from  the  Phragmidium,  especially  since  Krieger  has  found  and  described 
an  aecidium  form  that  corresponds  to  the  normal  type  of  such  stages  of 
Phragmidium,  and  which  is  now  accepted  as  the  first  stage  of  Ph. 
Rubi.  Since  the  aecidium  and  uredo  forms  of  Phragmidium  are  fre- 
quently so  similar,  it  is  not  at  all  unlikely  that  in  this  country  the  earlier 
stages  of  Ph.  Rubi  have  occasionally  been  classed  indefinitely  under 
the  uredo  form. 

Puccinia.  Still  another  genus,  Puccinia,  has  been  named  as  hav- 
ing connection  with  C.  nitens.  In  1885  Burrill  suggested  that  a  rela- 
tionship might  exist  between  Caeoma  nitens  and  Puccinia  Peckiana, 
as  both  were  found  in  Illinois  on  the  same  hosts.  Our  study  of  these 
fungi  has  led  to  the  belief  that  this  is  the  most  probable  explanation. 
Let  us  see  what  is  the  life  history  of  the  latter  fungus,  and  then  deter- 
mine what  evidence  there  is  to  offer  it  as  the  mature  form  of  the 
Caeoma. 

In  this  vicinity  the  fungus,  P.  Peckiana,  makes  its  appearance  on 
leaves  of  raspberry  and  blackberry  about  the  first  of  July,  and  has  been 
collected  on  them  as  late  as  September.  While  the  fungus  usually  occurs 
on  the  under  side  of  the  leaf,  an  occasional  sorus  is  found  on  the  margin  of 
the  upper  surface.  The  sori  are  so  small  as  generally  to  escape  atten- 
tion when  the  leaf  is  not  badly  affected,  and  sometimes  are  to  be  recog- 


1893*]        ORANGE   RUST   IX   RASPBERRIES  AND  BLACKBERRIES.  283 

nized  only  by  aid  of  a  magnifier.  They  frequently  occur  in  small, 
isolated  clusters,  but  often  the  leaf  is  abundantly  covered  with  them, 
and  then  the  peculiar  mottled  green  and  yellow  appearance  of  the  upper 
surface  serves  as  a  ready  aid  of  detection  to  the  trained  eye.  Cross 
sections  of  affected  leaves  show  mycelium  in  different  parts  running 
between  the  parenchyma  cells,  but  much  more  abundant  toward  the 
lower  surface.  Plants  known,  never  to  have  been  affected  with  the  Cae- 
oma  show  mycelium  confined  to  the  leaf.  The  mycelium  gives  rise 
directly  to  the  teleutospores;  and,  so  far,  these  only  have  been  found. 
They  are  formed  in  the  usual  method:  by  accumulation  of  mycelium 
near  the  under  surface;  formation  of  erect,  fertile  branches;  differentia- 
tion into  spores;  and  eventual  rupture  by  these  of  the  epidermis.  The 
mature  spores  are  quite  characteristic  in  their  appearance.  They  reach 
an  average  size  of  22  to  27  by  36  to  45  microns.  The  cell  walls  are  of 
a  reddish  brown  color,  and  of  nearly  uniform  thickness.  The  spores 
vary  considerably  as  to  shape,  especially  as  the  front  and  side  views  of 
the  same  spore  are  not  exactly  the  same.  Usually,  however,  the  apical 
cell  is  somewhat  triangular,  with  apex  covered  with  several  hyaline 
papillae.  Occasionally  these  papillae  have  been  seen  sparsely  covering 
the  whole  cell.  The  basal  cell  is  frequently  quadrangular,  with  the 
short,  hyaline,  fugacious  pedicle  at  one  corner  and  the  other  formed  by 
a  few  hyaline  papillae. 

Attempts  at  germination  of  these  spores  have  been  made  at  various 
times  of  the  year,  except  in  spring,  but  were  successful  only  on  one 
occasion.  About  the  middle  of  September  lately  gathered  spores  were 
placed  in  water,  and,  failing  to  show  signs  of  germination  at  the  end  of 
the  third  day,  the  slide  was  laid  aside  and  not  examined  until  the  spores 
had  been  a  week  in  the  water.  It  was  then  found  that  a  few  spores 
had  sent  out  germ  tubes  {Plate  4,  Jig.  24-29).  The  endospore  pierced 
the  exospore  through  a  small  opening,  and  immediately  enlarged  into 
the  natural  diameter  of  the  promycelium.  Apical  growth  of  this  took 
place  until  it  had  reached  a  length  two  or  three  times  the  diameter  of 
the  spore.  This  was  about  sufficient  to  empty  the  cell  of  its  contents. 
Both  apical  and  basal  cells  were  found  to  germinate,  though  but  a 
single  tube  was  produced  from  a  cell,  and  no  example  was  found  of 
both  cells  of  the  same  spore  germinating.  The  germination  ceased 
before  there  was  any  evidence  of  the  formation  of  promycelial  spores. 
The  germination  of  the  spores  at  this  time  of  the  year  suggests  that 
they  infect  their  host  through  some  other  place  than  the  leaves. 

So  much  for  the  life  history  of  this  fungus,  but  how  may  the 
phenomena  it  presents,  together  with  those  of  the  Caeoma,  be  inter- 
preted? These  will  be  considered  in  the  following  paragraphs  on  Dis- 
tribution, Hosts,  Life  Histories,  and  Artificial  Infection. 

Distribution.  While  the  distribution  of  this  Puccinia  has  not 
been  apparently  so  widespread,  or  so  frequently  reported  as  in  the  case 
of  the  Caeoma,  still  it  has  been  found  in  the  same  regions  only  with  the 


284  BULLETIN  NO.   29.  [December, 

latter.  Under  "Hosts"  of  the  Appendix  are  given  the  localities  in  which 
these  have  been  found.  The  effect  of  the  former  on  its  hosts  is  so  incon- 
spicuous, especially  when  compared  with  that  of  the  latter,  that  there  is 
no  doubt  that  its  range  will  be  more  widely  extended  when  a  careful 
search  is  made  for  it.  This  conclusion  is  based  on  experience  in  this 
locality;  for,  while  here  the  Caeoma  had  always  been  considered  com- 
mon, the  Puccinia  was  not,  until  a  careful  search  revealed  it  to  be  at 
least  as  common,  if  not  more  so,  than  the  former  fungus.  In  five 
localities  watched  during  the  past  three  years  both  forms  have  appeared 
abundantly. 

Hosts.  Naturally  enough,  the  Puccinia  having  been  less  frequently 
seen,  the  number  of  host  species  it  occupies  will  be  found  to  be  less,  as 
is  shown  in  the  Appendix;  but  such  as  it  does  attack  are  the  same  as 
those  upon  which  the  Caeoma  occurs.  Until  recently  only  one  was  re- 
ported from  Europe,  but  it  is  the  same  as  that  upon  which  the  Caeoma 
was  first  reported  over  seventy  years  ago.  In  this  vicinity  they 
leave  the  same  host  species  exactly,  and  on  the  cultivated  plants  both 
have  been  found  on  the  variety  known  as  the  Kittatiny.  In  a  patch  of 
these  affected  with  both  forms,  neither  was  seen  on  an  occasional  Snyder 
growing  there.  Not  only  are  they  found  occurring  in  the  same  locality 
and  on  the  same  species,  but  the  writer  has  recorded  hundreds  of  exam- 
ples where  they  occurred  on  the  same  individual.  This  is  forcibly 
shown  by  an  experiment,  given  in  detail  in  the  Appendix,  to  determine 
if  they  were  common  on  the  same  individual.  In  early  May,  as  soon 
as  the  spermagonia  began  to  show,  all  the  affected  plants  were  marked 
in  a  place  about  two  rods  wide  and  twenty  long.  Later,  in  June,  when 
the  aecidium  form  began  to  appear,  these  thirty-four  plants  were  again 
examined  and  it  was  found  that  all  had  developed  the  aecidium  stage. 
In  July,  they  were  examined  a  third  time,  and  Puccinia  Peckiana 
was  found  on  all  except  two  or  three  plants;  that  is,  about  90  per  cent 
were  affected.  In  these  exceptions  the  lower  leaves,  those  most  likely 
to  become  affected,  had  all  dropped  off.  As  some  might  think  that  the 
occurrence  of  the  Caeoma  and  the  Puccinia  on  the  same  plant  was  acci- 
dental, a  check  was  had  by  examining  for  the  Puccinia  plants  not  affected 
by  the  Caeoma.  Such  plants  of  course  would  not  be  so  likely  to 
become  infected  unless  they  were  close  to  those  affected  by  the  Caeoma. 
These  twenty  plants  were  chosen  at  random  from  those  near  and  away 
from  the  marked  plants.  Of  these,  thirteen  were  free,  and  seven  affected, 
or  65  per  cent  free.  The  seven  having  the  Puccinia  were  all  within 
three  feet  of  plants  affected  with  the  Caeoma;  while  of  those  free,  ten 
were  from  one  to  several  rods  from  the  nearest  marked  plant.  Cases 
have  also  been  found  in  which  the  same  leaf  had  sori  of  both  not  the 
twentieth  of  an  inch  apart  (Plate  i,fig.  2).  The  fact  that  the  Puc- 
cinia is  not  uniformly  found  with  the  Caeoma  is  easily  explained.  The 
two  forms  are  produced  from  entirely  different  myceliums,  and  as  the 
aecidium  form  is  so  destructive  to  the  leaves  it  attacks,  they  are  fre- 


1893-]        ORANGE  RUST  IN  RASPBERRIES  AND  BLACKBERRIES.  285 

quently  destroyed  and  have  fallen  off  before  the  time  of '  appearance  of 
the  teleutoform. 

Life  Histories.  Another  thing  that  forcibly  strikes  one  as  to  the 
connection  of  these  fungi  is  their  time  occurrence.  The  Caeoma,  abund- 
antly producing  spores  during  June,  gradually  disappears  just  as  the 
Puccinia  begins  to  appear  on  the  same  hosts  in  early  July.  As  the 
aecidiospores,  though  germinating  abundantly,  do  not  produce  the 
aecidium  stage,  what  could  be  more  natural  than  that  mature  spore 
forms,  occurring  on  the  same  hosts  and  at  the  proper  interval  of  time, 
should  be  connected  with  them?  Again,  what  other  influence  can  be 
had  when  the  Puccinia  spores  are  found  mostly  on  the  lower  leaves, 
where  the  aecidiospores  can  best  fall  from  the  affected  leaves  above? 
We  have  found  several  cases  of  a  leaf  unusually  affected  by  Puccinia 
that  was  just  beneath  a  Caeoma  infected  leaf.  Again,  these  aecidiospores 
gain  entrance  into  their  host  through  the  stomates,  and,  as  our 
culture  experiments  indicate,  through  those  of  Rubus;  the  stomates  of 
our  raspberries  and  blackberries  are  found  on  the  under  side  and  mar- 
gins of  the  upper  side  of  the  leaves;  the  Puccinia  sori  are  found  only  in 
these  places.  But  if  the  germ  tubes  of  the  aecidiospores  enter  through 
the  stomates  and  these  are  on  the  under  side,  what  avail  is  it  even  if  the 
Caeoma  affected  leaves  are  above?  The  Caeoma  affects  the  earliest 
leaves.  Many  leaves  on  lower,  unaffected  branches  are  beginning  to 
unfold  when  these  aecidiospores  are  mature.  These  young  leaves 
are  folded  together  conduplicately,  usually  with  the  margins  upward. 
The  lower  surface  is  thus  exposed  and  is  not  yet  well  protected  by 
hairs.  This  is  undoubtedly  the  time  when  most  of  the  leaves  are  enter- 
ed by  the  Puccinia  producing  agent,  a  fact  that  is  further  emphasized 
when  we  find  that  leaves  of  the  raspberry  affected  by  the  Puccinia  are 
not  usually  so  hairy  beneath  as  those  that  are  free.  The  production  of 
these  hairs  has  been  lessened  by  the  presence  of  the  fungus  in  the  leaf 
tissues,  and  to  effect  this  the  leaf  must  have  become  infected  before 
the  hairs  were  fully  developed.  In  examining  the  epidermis  of  leaves 
at  about  the  time  the  Puccinia  began  to  appear,  threads  of  mycelium  could 
frequently  be  seen  beneath  the  stomates,  and  in  a  few  cases  what  looked 
like  the  broken  end  of  an  upright  thread  seemed  to  be  coming  up 
between  the  guard  cells  (Plate  4,  fig.  jo).  We  have,  however,  never  been 
able  to  trace  this  to  an  aecidiospore.  Lastly,  the  Puccinia  spores  germ- 
inating in  fall,  possibly  in  spring  also,  when  infection  of  mature  leaves 
would  be  useless  and  when  the  young  underground  sprouts  are  in  con- 
dition for  infection,  seems  to  indicate  that  the  Puccinia  enters  the  plant 
through  these  underground  parts.  Since  the  spores  of  the  Puccinia  fall 
off  from  the  leaf  very  easily,  it  being  impossible  to  find  them  on  old 
leaves  in  spring,  the  spores  might  very  easily  be  washed  down  against 
the  young  shoots.  But  if  the  sporidia  of  the  Puccinia  stage  enter  these 
young  shoots  or  their  parts  they  do  not  give  rise  to  the  Puccinia  pro- 
ducing mycelium,  for  this  is  limited  to  the  leaves.  Why  not,  then,  give 
rise  to  the  mycelium  of  this  Caeoma? 


286  BULLETIN   NO.  29.  [December, 

Artificial  Infection.  But  after  all,  the  chief  proof  of  connection  of 
two  forms  is  by  artificially  producing  the  one  from  the  other.  Our  ex- 
periments along  this  line  have  been  fewer  and  unsatisfactory.  The 
plants  to  be  experimented  with  were  transplanted  in  spring  and  died 
before  inoculation  could  be  made,  or  before  time  for  judging  of  its 
effects.  It  is  hoped  to  continue  experiments  in  this  direction.  What 
one  might  call  natural  infection  seems  to  be  furnished  by  those  examples 
where  badly  Puccinia  affected  leaves  appeared  just  beneath  a  Caeoma 
infected  leaf.  However,  this  weak  point  in  our  evidence  is  strengthened 
by  the  experiments  of  Tranzschel  (1893),  whose  article  came  to  hand 
after  this  paper  had  been  written,  but  the  results  of  whose  experiments 
are  appended  to  this  paragraph.  In  1892  and  1893  he  undertook  infec- 
tion of  plants  of  Rubus  Saxatilis  with  the  aecidiospores  of  Caeoma  nitens. 
His  experiments  were  carried  on  at  the  botanical  gardens  of  the  Univer- 
sity of  St.  Petersburg.  June  18, 1893,  plants  both  in  and  out  of  doors  had 
the  spores  placed  on  the  leaves  of  their  young  shoots,  and  the  izth  of 
July  the  first  teleutospores  of  Puccinia  Peckiana  were  found  on  the 
plant  kept  indoors.  The  next  day  they  were  found  on  one  of  the  two 
plants  placed  outdoors,  and  by  the  24th  the  plants  experimented  with  had 
a  number  of  leaves  badly  affected.  He  also  reports  that  in  one  locality 
especially  examined  the  Puccinia  was  common  on  plants  previously 
affected  with  the  aecidium  stage  of  the  Caeoma. 

CONCLUSIONS. 

From  what  has  been  presented,  the  following  conclusions  may  be 
given: 

1.  The  so  called  Caeoma  nitens,  a  widespread  and  very  destruct- 
ive fungus  of  raspberries  and  blackberries,  has  been  proved  to  possess  a 
perennial   mycelium,   which  probably  first  gains  entrance  into  its  hosts 
through  very  young  underground  shoots. 

2.  This  mycelium,  following   the  growing  parts  of   the  plant,  in 
early  spring,    gives  rise  to  spermagonial,    and  soon    after   to   aecidium 
stages,  the  function  of  the  former  being  as  yet  unproved. 

3.  The  aecidiospores,  by  immediate  germination,  give  rise  to   a 
more  mature  spore  form,  which  is  in  no  way  connected  with  the  original 
mycelium. 

4.  These   aecidiospores   produce  this  form   by  infecting  the  host 
through  the  stomates  of  the  leaves,  and  evidence  now  proves  Rubus  as 
the  host  infected,  and  Puccinia  Peckiana  as  the  teleutoform  thus  produced. 

5.  Puccinia  Peckiana,  produced   on   the  under    side    of  leaves  of 
raspberry  and  blackberry,  germinates  its  spores  in  the  fall,  and  possibly 
in  early  spring,   and  probably   enters  its  hosts  through   young  under- 
ground shoots. 

6.  The  two  facts  that  the  mycelium  of  the   Puccinia  is  limited  to 
the  leaves,  and  that  the  mycelium  of  the  Caeoma  is  found  throughout  the 
plant   suggest  that  the   mycelium  of  the  aecidium  stage   has  its   origin 
from  the  germinating  Puccinia  spores. 


1893-]         ORANGE  RUST  IN   RASPBERRIES   AND  BLACKBERRIES.  287 


APPENDIX. 


NOMENCLATURE. 
*iS2O,  Caeoma  interstitiale,  Schlechtendal.   Horae  physicae  Berolinenses, 

p.  96. 

1822,  Aecidium  nit  ens,  Schweinitz.     Synop.  Fungi  Car.,  p.  69,  n.  458. 
1825,  Caeoma  (Aecidiitm)  luminatum,  Link.     In  Species   Plantarum,   T. 

VI,  P.  II,  p.  61,  n.  166. 
1825,  Caeoma  interstitiale.     Link  in   Species  Plantarum,  T.  VI,  P.  II, 

p.  32,  n.  89. 
1827,    Uredo   interstitialis,    Schl.    Sprengel    in    Systema    vegetabilium, 

V.  IV,  p.  574. 
1831,  Caeoma  (Aecidium)  luminatum,  Schweinitz.  North  American  Fungi, 

p.  293,  n.  2887.     Printed  in  1834. 
^1859,  Uredo  lucida,  Dietrich.     Blicke  in  die  Cryptogamenwelt  der  Ost- 

seeprovinzen,  Abth.  II,  p.  492. 

1869,  Puccinia  Peckiana,  Howe.     23   Rep.   Bot.,   N.  Y.  State  Museum, 
p.  57.     Printed  in  1872. 

1870,  Puccinia  tripustulata,  Peck.     24  Rep.  Bot,  N.  Y.  State  Museum, 
p»9i.      Printed  in  1872. 

1893,  Puccinia  interstitiale  (Schlechd.),  Tranzschel.      Hedwigia,  Heft. 

5»  P-  257- 

So  far  as  can  be  made  out  from  the  above  and  other  references,  the 
the  history  of  the  fungus  is  as  follows: 

In  1817,  Ehrenberg,  while  on  a  journey,  made  some  collections  of 
fungi  in  Kamtchatka.  Schlechtendal,  in  1820,  while  working  over  the 
Caeoma  of  this  collection,  came  across  one  on  Rubus  arcticus,  which  he 
described  as  a  new  species  under  the  title  of  Caeoma  interstitiale.  Two 
years  later,  Schweinitz,  of  America,  in  publishing  the  fungi  collected  in 
Carolina,  also  described  as  new  a  fungus  on  Rubus  strigosus,  to  which  he 
gave  the  name,  Aecidium  nit  ens.  In  1825,  Link,  writing  up  descriptions 
of  known  fungi, gave  both  Schlechtendal's  fungus  and  Schweinitz5  fungus, 
in  the  latter  case,  however,  placing  the  fungus  in  the  genus  Caeoma  and 
retaining  Aecidium  as  a  subgenus.  Then,  without  authority  as  recognized 
to-day,  he  rejected  the  specific  term  applied  by  Schweinitz  and  substi- 
tuted "luminatum"  for  the  same.  When  Sprengel  published  the  Systema 
Vegetabilium,  in  1827,  he  recognized  the  Asiatic  and  American  forms  as 
the  same,  for  he  gave  Aecidium  nitens  Schw.  as  a  synonym  for  Uredo 
interstitialis,  Schl.  Schweinitz,  in  his  second  publication,  in  1831,  accepted 
the  specific  name  as  exchanged  by  Link,  but  added  his  own  name  as  the 
authority.  According  to  Tranzschel  the  fungus  was  again  described 


*  References  marked  thus  (*)  I  have  not  been  able  to  examine  personally. 


288  BULLETIN  NO.  29.  \December, 

as  new  in  1859  by  Dietrich,  who  used  the  name  Uredo 
lucida.  Streinz  (1862),  in  his  Nomenclator  fungorum,  placed 
the  forms  of  Schweinitz  and  Schlechtendal  together,  recognizing  "inter- 
stitialis"  as  the  specific  term;  and  Oudemans  (1891),  in  a  note  in  Hed- 
ijuigia,  again  called  attention  to  their  identity.  Some  considerable  con- 
fusion has  been  caused  by  Karsten  (1879),  who  described  this  Caeoma 
as  the  Aecidium  form  of  Phragmidium  Rubi.  Winter  (1884),  used  this 
description  of  Karsten's,  but  stated  that  he  had  never  seen  this  stage  of 
Phragmidium,  but  in  1885  he  evidently  recognized  the  Caeoma  as  dis- 
tinct. Krieger,  however,  by  finding  and  describing  the  real  aecidium 
form  of  Phragmidium  Rubi  has  cleared  up  this  difficulty.  It  seems 
from  the  references  to  be  found  that  Trelease  first  called  the  fungus 
Caeoma  nitens,  and  that  Curtis  is  responsible  for  Uredo  nitens  and  Uredo 
luminata.  The  above  terminalogy  not  being  sufficient  for  the  botanists  of 
to-day,  various  combinations  have  been  made  and  Schweinitz  has  been 
burdened  as  the  authority  in  most  cases.  Such  are  Uredo  luminata,  Caeoma 
{Uredo)  luminatum,  Uredo  {Caeoma)  nitens,  Uredo  caeoma-nitens,  Caeoma 
nitens,  Caeoma  luminatum,  Uredo  luminatum,  Uredo  nitens,  Aecidium 
luminatum. 

The  history  of  the  mature  stage  is  briefer,  perhaps  on  account  of 
its  late  discovery.  In  1869  Howe  described  a  new  Puccinia  found  on 
the  raspberry  as  P.  Peckiana;  while  the  next  year,  Peck,  finding  it  on 
the  blackberry,  and  thinking  it  different,  described  it  as  P.  tripustulata. 
Burrill,  in  1885,  called  attention  to  these  as  identical,  adding  that  they 
were  now  so  considered  by  Peck.  Lately,  Tranzschel,  by  culture  ex- 
periments connecting  the  Caeoma  and  the  Puccinia,  has  taken  the  first 
specific  name  given  to  the  Aecidium  form  and  called  the  fungus  Puc- 
cinia interstitiale  (Schlechd).  We  believe,  however,  with  Farlow,*  and 
and  it  seems  to  be  the  usual  method,  that  when  such  forms  are  found  to 
be  connected  the  specific  name  of  the  mature  stage  should  be  retained, 
in  which  case  Puccinia  Peckiana,  Howe,  is  still  proper  and  should  be 
retained. 

DISTRIBUTION. 

From  notes  printed  in  various  publications,  the  following  distri- 
bution of  the  fungus  has  been  obtained. 

The  aecidium  stage  has  been  reported  as  follows  in  the  United 
States — Carolina,  Schweinitz;  Connecticut,  Thaxter;  Georgia,  Ravenel; 
Illinois,  Burrill;  Iowa,  Arthur;  Kansas,  Kellerman;  Maryland,  Brunk; 
Massachusetts,  Sprague;  Minnesota,  Sheldon;  Mississippi,  Earle;  Mis- 
souri, Demetrio;  Nebraska,  Webber;  New  Hampshire,  Seymour;  New 
Jersey,  Britton;  New  York,  Peck;  Ohio,  Detmers;  Pennsylvania, 
Schweinitz;  Texas,  Jennings;  West  Virginia,  Millspaugh;  Wisconsin, 
Trelease.  In  Canada — Ottawa,  Ellis  &  Everhart.  In  Europe — Bavaria, 


*Proceedings  American  Academy  of  Arts  and  Sciences,  1883,  p.  66. 


ORANGE  RUST  IN  RASPBERRIES  AND  BLACKBERRIES. 


289 


Allescher;  Finland,  Kihlman;  France,  Cornu;  Scandinavia,  Eriksson ; 
Russia, Tranzschel.  In  Asia — Siberia, Thumen ;  Kamtchatka,Schlechten- 
dal.  In  European  and  Asiatic  Russia,  Tranzschel  also  gives  the  following : 
Gouv.  St.  Petersburg,  Gouv.  Archangelsk,  Gouv.  Moscow,  Gouv.  Esth- 
land,  N.  Ural,  and  Minussinsk,  and  region  of  Semipalatinska,  and 
Enisseisk. 

The  stations  of  the  teleutostage  are  more  limited  and  as  follows: 
In  the  United  States — Illinois,  Burrill;  New  York,  Howe;  Massachu- 
setts, Farlow;  Missouri,  Galloway.  In  Europe — Lapland,  Lagerheim; 
Russia,  Tranzschel. 

HOSTS. 

The  hosts  of  the  aecidum  stage  are  as  follows:  In  the  United 
States — Rubus  Canadensis,  R.  hispidus,  R.  occidentalis,  R.  strigosus,  R. 
triflorus,  R.  trivialis,  R.  villosus.  In  Europe  and  Asia — R.  saxatilis,  R. 
arcticus. 

For  the  teleutostage  hosts  have  been  reported  as  follows:  United 
States — Rubus  occidentalis,  R.  strigosus,  R.  villossus.  Europe — R. 
arcticus,  R.  saxatilis. 

INDIVIDUAL  HOSTS, 

The  following  table  proves  an  intimate  relationship  existing  be-- 
tween  this  Caeoma  and  the  Puccinia,  as  shown  by  their  occupancy  of 
the  same  individual  plants. 

INDIVIDUAL  HOSTS  OF  CAEOMA  AND  PUCCINIA. 


Spermagonia,  May  lyth. 

Caeoma,  June  gth. 

Puccinia,   July  6th-i4th. 

i.  Raspberry.  Leaves  of 
old  and  new  shoots  af- 
fected. 

Affected. 

Old  with  few  lower  leaves 
still  present  and  badly 
affected. 

2.  Rasp.     Old   and   new 
affected. 

Old  affected. 

Old    nearly   all  dead,  like 
lower,  new  badly  affect'd. 

3.  Rasp.  Old  affected, 
new  shoots  not  yet  de- 
veloped. 

Old  affected 

Dead,  but  some  dead  leaves 
slightly  affected. 

4.  Rasp.  Old  and  quite 
young  new  affected. 

Old  affected. 

Dead,  and  leaves  all  dried 
up. 

5.  Rasp.  Old  free  The 
single  new  affected. 

Old  free.     New  affected. 

Failed  to  find  plant. 

6.  Rasp.  No  old.  The 
single  new  partly  affect'd 

One  new  affected. 

One  lower  leaf  affected^ 
near  Caeoma  affected 
leaf. 

7.  Rasp.  Three  old  free. 
Two  new  affected 

Two  old  free.      Two  new 
affected. 

One  old,  lower  leaves  bad- 
ly affected;  single  new 
affected  live  leaf. 

8.  Rasp.  Old  free.  New 
affected. 

Old  free.   Four  new  affect- 
ed. 

Old,  nearly  dead,  slightly 
affected. 

9.  Rasp.  One  old  free. 
Three  new  affected. 

One  old  free.     Three  new 
affected. 

Several  new,  nearly  dead, 
free.  One  old  affected. 

10.  Rasp.  Three  old  free. 
Many  small  new  mostly 
affected. 

Three  old,  three  new,  free. 
Four  new  affected. 

Old  and  new  affected,  some 
badly. 

290  BULLETIN   NO.   29.  [December, 

INDIVIDUAL  HOSTS  OF  CAEOMA  AND  PUCCINIA — Continued. 


Spermagonia,  May  lyth. 

Caeoma,  June  gth. 

Puccinia,  July  6th-i4th. 

ii.  Rasp.  One  old  free. 
Five  new  affected. 

One  old  free.      Three  new 
affected. 

Several  new,  without  low- 
er leaves,  free.   One  old, 
one  new,  affected. 

12.  Rasp.  One  old  free. 
Bunch  of  new  affected. 

Two  old,    one  new,    free. 
Two  new  affected. 

Old  and  new  affected. 

13.  Rasp.  One  old  free. 
One  new  affected. 

One  old  free.      One  new 
affected. 

Two  new,  with  few  lower 
leaves,   free.       One  old 
affected. 

14.  Rasp.  One  old,  one 
new  affected. 

One  old  affected. 

Dead,  but  plant  near  bad- 
ly affected. 

15.  Rasp.  One  new  affect- 
ed. 

Failed  to  find  plant. 

Three  new,  lower    leaves 
affected. 

16.  Rasp.  Twoold,  some 
new,  slightly  affected. 

Twoold,  two  new,  affected. 

Two    old,     nearly     dead, 
slightly     affected;    new, 
lower  leaves  slightly  af- 
fected. 

17.  Rasp.  One  new  affect- 
ed. 

One  new  affected. 

One     new,    lower     leaves 
mostly   dead;    but   with 
one  affected. 

1  8.  Rasp.  One  old  free. 
Several  new  affected. 

One  old  free.      Two  new 
affected, 

Failed  to  find  plant. 

19.  Rasp.  Several  old 
free.  Several  small  new 
slightly  affected. 

One   old,    five   new,    free. 
Two  new  slightly  affect- 
ed. 

A    few    lower   leaves    af- 
fected. 

20.  Rasp.  One  weak  old 
free.  Bunch  of  new 
affected. 

Practically  dead. 

Practically  dead,  but  with 
single  live  leaf  affected. 

21.  Rasp.  Bunch  of  new 
affected. 

One  new  affected. 

Slightly  affected. 

22.  Rasp.  One  old,  sev- 
eral new,  affected. 

One  old  free.      One    old, 
three  new,  affected. 

Affected. 

23.  Rasp.  Two  old,  one 
new,  affected. 

One  new  free.     One   old, 
one  new,  affected. 

One  new,  with  lower  leaves 
affected. 

24.  Rasp.  One  old,  near- 
ly dead;  several  new, 
affected. 

One  old,  five  new,   affect- 
ed. 

Practically  dead,  with  two 
or  three  affected  leaves. 

25.  Rasp.  Several  old 
affected.  No  new  of  im- 
portance. 

Failed  to  find  plant. 

Dead. 

26.  Rasp.  Two  old  free. 
Three  new  affected. 

One  old  free.     Three  new 
affected. 

One  old,  two  new,  affected. 

27.  Rasp.  One  old  near- 
ly dead,  some  new,  af- 
fected. 

Abundantly  affected. 

Practically  dead,  free. 

28.  Blackberry.  Old  near- 
ly dead,  some  new,  af- 
fected. 

Abundantly  affected. 

Lower  leaves  affected. 

29.  Blackberry.  One  old 
nearly  dead,  some  new, 
affected. 

Abundantly  affected. 

Practically  dead,  some  low- 
er leaves  affected. 

1893-]        ORANGE   RUST  IN   RASPBERRIES  AND   BLACKBERRIES.  29 1 

INDIVIDUAL  HOSTS  OF  CAEOMA  AND  PUCCINIA — Continued. 


Spermagonia,  May  lyth. 

Caeoma,  June  gth. 

Puccinia,  July  6th-i4th. 

30.  Rasp.  Old  nearly 
dead,  some  new,  affect'd. 

Affected. 

Old  without  leaves;  new 
without  lower  leaves; 
upper  free. 

31.  Rasp.  One  old  free. 
One  new  affected. 

Abundantly  affected. 

A  few  lower  leaves  slightly 
affected. 

32.  Rasp.  Two  old  free. 
One  old,  some  new,  af- 
fected. 

Abundantly  affected. 

Failed  to  find  plant. 

33.  Rasp.  Two  old,  some 
new,  affected. 

Abundantly  affected. 

Old  without  leaves;  new 
free. 

34.  Rasp.  Old  free.  New, 
affected. 

Abundantly  affected. 

Old  affected;  new,  without 
lower  leaves,  free. 

A  number  of  the  above  plants  were  affected  by  the  spermagonia  and 
the  aecidium  stage  on  the  new  shoots  only.  This  does  not  necessarily 
mean  that  those  plants  were  affected  for  the  first  time,  for  the  fungus 
may  have  had  such  a  disastrous  effect  on  those  shoots  infected  the  pre- 
vious year  as  to  have  killed  all  of  them,  a  thing  quite  apt  to  occur.  It 
will  also  be  seen  that  a  number  of  plants  were  killed  entirely.  Of  the 
living  plants  there  were  only  three  found  in  June  that  were  not  affected 
with  the  Puccinia,  and  these  had  their  leaves  so  destroyed  by  the  aecidium 
stage  as  to  render  subsequent  infection  unlikely. 

The  following  serves  as  a  sort  of  check  to  the  above.  These  plants 
were  examined  at  the  same  time  as  the  above  for  the  Puccinia.  They 
were  in  the  same  locality,  and  at  varying  distances  from  plants  affected 
by  the  aecidium  stage;  but,  as  none  had  been  affected  by  this  stage,  their 
chance  of  being  host  to  the  Puccinia  depended  considerably  on  their 
distance  from  plants  having  the  Caeoma.  There  were  thirteen  plants  free 
and  seven  on  which  the  Puccinia  was  found.  All  the  affected  ones  were 
near  plants  that  had  the  aecidium  form. 

a.  Raspberry.    A  healthy  plant.  Two  old,  two  new  shoots,  free.    Several  rods  from 

plants  affected  with  aecidium  stage. 

b.  Rasp.     Rather  vigorous.     One  old,  two  new,  free.     Near  a. 
Rasp.     Vigorous.     Single  new,  apparently  free.     Near  a. 
Rasp.     Sickly.     One  dead  old,  one  new,  free.     Near  a. 

Rasp.     Healthy,    One  old,  two  new,  free.  Two  or  three  rods  from  affected  plants. 

Rasp.     Rather  sickly.     Free.      Near  e. 

Rasp.     Rather  sickly.     One  dead  old,  one  new,  free.     Near  e. 

Rasp.      One  new  free.     One  old   with   single    leaf  slightly  affected.     Three   feet 

from  affected  plant  27. 

i.    Blackberry.     Healthy.     One  old,  one  new,   free.     Five  feet  from  affected  plant  27 . 
j.    Rasp.     Vigorous.     One  old,  one  new,  free.      Three  feet  from  affected  plant  27. 
k.  Rasp.     Two  new  free.     One  old,  one  new,  rather  abundantly  affected.     Two    feet 

from  affected  plants  22,  23,  24,   25. 
1.    Rasp.     One  new  free.     One  old  affected.     Near  k. 
m.  Rasp.     One  old,  one  new,  free.     One  old  slightly  affected.     Near  k. 
n.   Rasp.     One  old,  several  new,  affected  abundantly  on  lower  leaves.     Near  k. 
o.   Rasp.     One  old,  two  new,  rather  abundantly  affected.     Near  k. 
p.   Rasp.     Several  old  and  new  free.     Ten  feet  from  two  affected  plants. 


292  BULLETIN  NO.   29.  [December, 

q.  Rasp.  Two  old,  two  new,  free.     Near  p. 

r.    Rasp.  One  old,  one  new,  free.     Near  p. 

s.   Rasp.  One  old,  one  new,  free.     Close  to  an  affected  plant. 

t.    Rasp.  Old  and  new  affected.     Close  to  affected  plant. 

EXSICCATI. 

In  exsiccati  the  Caeoma  and  Puccinia  here  considered,  on  the  dates 
£iven,  were  distributed  under  different  names  as  follows: 
1852,  Aecidium  luminatum,  Schw.,  Ravenel's  Fungi  Caroliniani,  V.  i,  n.  91. 
1876,  Uredo  luminatum,  Curtis,  on  Rubus  Canadensis,  De  Thiimen's  Mycotheca  Uni- 

versalis,  C.  V.,  n.  446. 

1879,  Uredo  luminatum,  (Schw.),  on  Rubus,  Ravenel's  Fungi  Americani,  C.  Ill,  n.  276. 
1879,  Caeoma  luminatum,  (Schw.),  on  Rubus  Strigosus,  Ellis'  N.  A.  F.,  C.  Ill,  n.  277. 
1885,  Caeoma  nitens,  (S.),  on  Rubus  villosus,  K.  saxatilis,  Rabenhorst's  Fungi  Europaei, 

C.  XXXIII,  n.  3225,  a.  b.  c. 
*i887,  Caeoma   nitens,  (Schw.),    Eriksson's  Fungi   parasitici   scandinavici,    exsiccati, 

F.  IV. 
*i889,  Caeoma  nitens •,  Schw.,  on  Rubus  villosus,  Kell.  &  Swingle's  Kans.  Fungi,  F.  II, 

n.  31. 
*i89o,  Caeoma  nitens,  Schwein,  on  Rubus  saxatilis,  Allescher  &  Schnabl's  Fungi  Bava- 

rici  exsiccati,  C.  I. 
1890,  Caeoma  nitens,  (S.),  on  Rubus  Canadensis,  R.  villosus,   Seymour  &   Earle's  Eco. 

Fungi.  F.  I.,  n.  27,  28. 

1879,  Puccinia  Peckiana,  Howe,  on  Rubus  occidentalis,  Ellis'  N.  A.  F.,  C.  Ill,  n.  261. 
1890,  Puccinia  Peckiana,  Howe,  on  Rubus  villosus,    Seymour  &  Earle's  Eco.  Fungi,  F. 

I.,  n.  26. 

LITERATURE. 

The  following  references  are  such  as  have  been  used  in  the  prepa- 
ration of  this  paper.  Scattered  through  agricultural  and  horticultural 
papers  are  notes  on  the  "Orange  Rust,"  which  we  have  not  cited,  save 
in  one  or  two  instances.  While  it  has  been  the  intention  to  include  all 
articles  or  notes  of  scientific  importance  on  this  subject,  it  is  quite  prob- 
able that  some  may  have  escaped  observation. 

Allescher,  1888,  Bot.  Centralblatt,  B.  XXXVI,  p.  287,  notes  finding  Caeoma  nitens  on 
Rubus  saxatilis  near  Allach  in  1878,  and  mistaking  it  for  a  form  of  Phragmidium 
Rubi. 

Arthur,  1884,  Bull.  Iowa  Agr.  Coll.,  p.  164,  lists  C.  nitens  as  occurring  on  black- 
berry in  that  state. 
Bessey,  1885,  Rep.  Amer.  Pom.  Soc.,  p.  43,  lists  C.  luminatum  among  the  injurious 

fungi  of  horticulturists. 

Botanisches  Centralblatt,  1887,  B.  XXIX,  p.  158,  gives  C.  nitens  as  one  of  the  fungi 
in  the  IV  Fas.  Fungi  parasitici  scandinavici,  which  appeared  about  this  date. 
Brendel,  1887,  Flora  Peoriana,  p.  69,  lists  C.  nitens  from  Peoria  Co.,  111. 
Britton,  1889,  Geol.  Surv.  New  Jersey,  V.  II,  P.  I.  p.  503,  gives  Uredo  luminata  on 

R.  strigosus  from  New  Jersey. 

Brunk,  1890,  Ann.  Rep.  Md.  Agr.  Coll.  and  Ex.  Sta.,   p.  115,  mentions  twenty  varie- 
ties of  blackberries  affected  by  C.  nitens,  and  gives  notes  on  degree  of  affection. 
1891  Rep.  same  publication,  pp.  389  &  416,  gives  results  of  spraying  and  notes 
on  varieties  affected. 
Burrill,  1882,  Agr.  Review,  p.  88,  gives  an  account  of  Caeoma  luminatum. 

1885,  Parasitic  Fungi  of  Illinois,  P.  I,  pp.  178,  220,  gives  scientific  descriptions 

of  C.  nitens  and  P.  Peckiana,  and  suggests  relationship. 

1885,    Rep.   111.    Industrial   Univ.,   p.    115,    writes  scientific  description  of    P. 


1893-]        ORAXGE  RUST   IN  RASPBERRIES  AND   BLACKBERRIES.  293 

Peckiana,  also  p.  138  same,  of  C.   nitens,   and  suggests  a  connection  between 

them. 

1885,  Prairie  Farmer,  V.  LVII.  p.  762,  gives  detailed  structure  of  C.  nitens,  etc. 

1885,  Reprint  from  Amer.  Soc.  Micr.,  pp.  3,  8,   gives  general  description  and 

possible  connections  of  C.  nitens. 

*Cobb,  1887,  List  PI.  Amherst,  p.  39,  gives  Uredo  luminata. 
Cooke,  1878,  Grevillea,  V.  VII,  p.  46,  lists  Uredo  luminatum  from  Georgia. 
Cornu,  1881,  Bull.  Soc.  Bot.  France,  p.   145,  gives  an  account  of  finding  Ae.  lumi- 
natum on  Rubus  in  France,  mentioning  it  as  new  to  Europe. 

Cragin,  1885,  Bull.  Washburn  Coll.,  V.  I,  n.  2,  p.  68,  lists  C.  luminatum  from  Kansas. 
*Curtis,  1867,  Bot.  N.  Car.,  p.  122,  gives  Uredo  luminata. 

Day,  1883,  Cat.  Plants  of  Buffalo  and  vicinity,  gives  Uredo  luminata  in  the  list. 
Detmers,  1891,  Ohio  Ex.  Sta.,  Bull.  No.  6,  p.  127,  makes  a  general  description  of  C. 

nitens  with  its  effect  on  host. 

1892,  Same  Pub.,  V.  V,  No.  7,  p.  137,  mentions  finding  what  seems  to  be  an 
uredo  stage  of  C    nitens.  etc. 

1893,  Same  Pub.,  Tech.  Series,  V.  I,  No.  3,  p.  180,  describes  further  this  sup- 
posed uredo  form  of  Uredo  (Caeoma)  nitens,  etc. 

De  Toni,  1888,  Saccardo's  Sylloge  Fungorum,  V.  VII.,  P.  II,  p.  866,  gives  synonyms, 

hosts,  and  description  of  Uredo  (Caeoma)  nitens,  also  p.  699  treats  P.  Peckiana 

similarly. 
Dietel,  1887,  Botanisches  Centralblatt,  B.   XXXII,   p.  87,    makes  mere  reference  of 

variability  of  spores  of  P.  Peckiana,  as  shown  by  Lagerheim,  1887. 

1892,  Bot.  Centralblatt,  B,  XLIX,   p.  270,   gives  reference  to  two  articles  on 

Russian  Uredineae  by  Gobi  and  Tranzschel. 
^Dietrich,    1859,  Blicke  in   die  Cryptogamenwelt  der   Ostseeprovinzen,  abth.  II,  p. 

492,  describes,  according  to  Tranzschel,  this  Caeoma  as  a  new  species,  Uredo 

lucida. 
Earle,  1889,  U.  S.  Dept.  Agr.,  Sec.  Veg.   Pathol.,  Bull.  No.  XL,  pp  84,  85,  88,  gives 

results  of  spraying  with  Bordeaux  mixture  blackberries  affected  with  C.  nitens. 
*Ellis,  1889,  Cat.  PI.  New  Jersey,  503,  gives  Uredo  luminata. 
Ellis  &  Everhart,  1885,  Journal  of  Mycology,  V.  I,  p.  86,  give  C.  luminatum  on  R. 

triflorus  from  Ottawa,  Canada. 
Ex.  Sta.  Record,  Vol.  II,  pp.   32,  455,  482;  V.  Ill,   pp.   161,    313,   411,  722,  makes 

reference  to  different  Ex.  Sta.  notes  on  C.  nitens. 
Evans,  1893,  Handbook  Ex.  Sta.  Work,   U.  S.  Dept.  Agr.,  p.  283,  gives  account  of 

general  appearance  of  C.  nitens. 
Farlow,  1876,  Bull.  Bussey  Institution,   p.  432,   lists   P.    Peckiana  as   occurring   in 

Massachusetts. 

1883,    Proc.   Amer.   Academy  Arts  and  Sciences,   p.   76,   gives  a  general  de- 
scription of  appearance  of  Ae.  nitens,  and  suggests  that  this  may  prove  to  be  a 

heteroecious  fungus. 
Farlow  &  Seymour,  1888,  Host  Index  U.  S.  Fungi,  p.  37,  give  hosts  and  synonyms 

of  C.  nitens  and  P.  Peckiana. 

*Frost,  1875,  Cat.  PI.  Amherst,  p.  84,  lists  Uredo  luminata. 
Galloway,  1889,  U.  S.  Dept.  Agr.,  Bot.  Div.,  Bull.  VIII,  pp.   56,    58,   lists  C.  nitens 

and  P.  Peckiana  from  Missouri. 

1889,  Rep.  U.  S.  Dept.  Agr.,  p.  416,  speaks  of  spraying  experiments  made  by 

Earle.     Printed  in  1890. 
Gardner's    Monthly,    1871,    pp.    211,    266,    correspondents   give   notes    on     "orange 

rust"  of  blackberry,  treatment,  etc. 
Hoffman,   1863,   Index  Fungorum,  p.   3,   lists  Ae.   luminatum  with   "nitens"  as  the 

synonym. 
Howe,  1869,  (23)  Rep.  Bot.  N.  Y.  State  Museum,  p.  57,  gives  description  of  a  new 

fungus,  Puccinia  Peckiana,  on  Rubus  occidentalis.     Printed  in  1872. 


294  BULLETIN   NO.   29.  [December, 

Humphrey,  1890,  Ann.   Rep.  Mass.  Ex.  Sta.,  p.  224,  mentions  C.  nitens  as  common 

there,  etc.     Printed  in  1891. 
Jennings,  1890,   Texas  Ex.  Sta.,   Bull.  No.  IX,  p.  23,  mentions  C.  nitens  as  quite  a 

drawback  to  culture  of  blackberry,  and  mentions  it  as  also  found  on  wild  plants 

of  R.  trivialis. 
Journal  of  Mycology,  1889,  p.  103,  gives  reference  to  Lagerheim's  1889  article  and 

p.  161,  lists  C.  nitens  as  in  Kellermann  &  Swingle's  Kans.  Fungi,  Fas.  II. 
Kellerman,  1885,  Washburn  Coll.  Bull.,  V.   I,  n.  2,  p.  74,  gives  host  of  C.  nitens  in 

Kansas. 
Karsten,    1879,    Mycologia  Fennica,   P.    IV,  p.   51,   describes  what  is  probably   C. 

nitens  as  aecidium  form  of  Phragmidium  bulbosum  (Ph.  Rubi). 
Lagerheim,  1887,  Botanisker  Notiser,  p.  60,  gives  an  account  of  finding  P.  Peckiana 

on  R.  arcticus  in  Lapland,  discusses  forms  of  this  fungus  as  found  in  different 

localities,   and  suggests  C.    nitens  as  a  stage  of  Ph.   Rubi  rather  than  of  P. 

Peckiana. 

1889,  Hedwigia,  B.  XXVIII,  H.  2,  p.  no,  treats  of  distribution,  of  hosts,  and 
of  the  relationship  of  C.  nitens  to  other  forms,  and,  as  Krieger  has  found  the 
aecidium  stage  of  Ph.  Rubi,  now  thinks  the  Caeoma  heteroecious. 

1890,  Hedwigia,  p.  173,  gives  mere  reference  to  variability  of  position  of  germ 
pore  of  P.  Peckiana. 

Link,  1825,  Species  Plantorum,  T.  VI,  P.  II,  p.  61,  n.  166,  describes  C.  luminatum 
and  gives  its  host  and  locality  as  taken  from  Schweinitz,  but  instead  of  adopt- 
ing the  latter's  name  for  the  fungus  gives  it  one  on  his  own  account. 
Same,  p.  32,  n.  89,  gives  description,  hosts,  locality  and  name  of  Schlechtendal's 
(1820)  Caeoma  interstitiale, 

Ludwig,  1884,  Bot.  Cent.,  B.  XX,  p.  356,  reviews  Trelease's  1884  article. 

1887,  Botanisches  Centralblatt,  B.   XXXI,  p.  162,  makes  a  short  abstract  of 
Lagerheim's  1887  article. 

Magnus,  1890,  Separat-Abdruck  aus  Hedwigia,  H.  6,  gives  C.  nitens  as  one  of  the 
interesting  fungi  in  Cent.  I,  Fungi  Bavarici. 

Millspaugh,  1892,  West  Va.  Agr.  Ex.  Sta.  Bull.,  n.  24,  p,  509,  gives  C.  nitens  as 
found  in  that  state  on  R.  hispidus. 

Newcombe,  1891,  Jour.  Mycology,  Vol.  IV.  p.  106,  proves  mycelium  of  C.  nitens  to 
be  perennial  in  its  host.  Remarks  by  Galloway  on  consequent  treatment. 

New  York  Agr.  Ex.  Sta.,  Bull.  n.  36,  p.  641,  mentions  orange  rust  as  a  troublesome 
disease  of  raspberry. 

Oudemans,  1891,  Hedwigia,  H.  3,  p.  178,  refers  to  Caeoma  interstitiale  published 
by  Schlechtendal  in  1820,  it  being  collected  by  Ehrenberg  in  1817  in  Kam- 
tchatka  on  Rubus  arcticus,  states  that  the  illustration  given  of  this  fungus  corre- 
sponds exactly  with  that  of  C.  nitens,  which  must  now  be  known  as  C.  inter- 
stitiale, as  this  one  was  published  two  years  earlier. 

Peck,  1868,  (22nd)  Rep.  Bot.  N.  Y.  State  Museum,  p.  92,  lists  Uredo  luminata  as 
common  on  Rubus.  Printed  in  1869. 

1870,  (24th)  Rep.  p.  91,  gives  scientific  description  of   Puccinia  tripustulata, 
n.  s.  found  on  Rubus  villosus.     Printed  in  1872. 

1871,  (25th)  Rep.  pp.  113,  114,  gives  scientific  descriptions  of  P.  tripustulata, 
Pk.  and  P.  Peckiana,  Howe,  which  at  that  time  he  considered  distinct.     Printed 
in  1873. 

1873,  (27th)  Rep.  p.  77,  notes  Uredo  luminata  as  rapidly  becoming  a  serious 
drawback  to  the  culture  of  blackberries  and  raspberries.     Printed  in  1875. 
1875,  (2gth)  Rep.   p.  72,  lists  P.  Peckiana  and  P.  tripustulata,  also  p.   75,  lists 
Uredo  luminata  as  found  there  on  R.  villosus,  R.  Canadensis,  R.  occidentalis, 
R.  strigosus.     Printed  in  1878. 

Richards,  1893,  Proc.  Amer.  Acad.  Arts  and  Sciences,  p.  31,  treats  of  development  of 
the  spermagonia  of  C.  nitens,  and  states  that  they  do  not  originate  in  one 
greatly  enlarged  epidermal  cell. 


1893-]        ORANGE   RUST    IN   RASPBERRIES  AND  BLACKBERRIES.  295 

*Schlechtendal,  1820,  Horae  physicae  Berolinenses,  p.  96,  t.  20,  f.  13.,  describes  and 
figures  C.  interstitiale  as  new,  it  being  collected  by  Ehrenberg  in  Kamtchatka 
in  1817  on  R.  arcticus. 

Schroeter,  Ein  Beitrag  zur  Kenntniss  der  nordischen  Pilze.  p.  7,  gives  C.  nitens  as 
found  in  Sweden. 

Schweinitz,  1822,  Synop.  Fungi  Carolina,  p.  69,  n.  458,  describes  Ae.  nitens,  n.  s. 
on  Rubus  strigosus. 

1831,  North  Amer.  Fungi,  p.  293,  n.  2887,  gives  his  former  Ae.  nitens  as 
Caeoma  (Aecidium)  luminatum,  Schw.,  his  specimen  this  time  being  from 
Pennsylvania.  Printed,  1834. 

Scribner,  1886,  Rep.  U.  S.  Dept.  Agr.,  p.  133,  lists  C.  nitens  from  Michigan.  Printed 
1887. 

Seymour,  1886,  Reprint  from  Minn.  Hort.  Rep.,  V.  XIV,  gives  some  facts  concern- 
ing life  history  of  C.  nitens. 

1887  Amer.  Naturalist,  p.  1115,  notes  a  more  erect  and  rigid  growth  of  plants 
attacked  by  C.  nitens. 

Sprague,  1856,  Proc.  Boston  Nat.  Hist.  Soc.,  p.  328,  lists  Uredo  nitens  as  occurring 
in  Massachusetts. 

Sprengel,  1827,  L.  Sys.  Veg.  i6ed.,  V.  IV,  p.  574,  gives  scientific  description  of 
Uredo  interstitialis,  Schl.,  which  he  considers  the  same  as  Aecidium  nitens, 
Schw. 

Streinz,  1862,  Nomenclator  fungorum,  p.  644,  n.  10757,  gives  Uredo  interstitialis, 
Spr.,  with  Ae.  nitens,' Schw.,  C.  interstitiale,  Lk.,  and  C.  luminatum,  Lk.  as 
synonyms. 

Thaxter,  1889,  Ann.  Rep.  Conn.  Ex.  Sta.,  p.  172,  gives  C.  nitens  as  common  on 
cultivated  and  wild  raspberries  and  blackberries,  and  suggests  method  of  treat- 
ment. Printed  in  1890. 

*Thumen,  1880,  Beitrage  zur  Pilz-Flora  Sibiriens,  III,  p.  14  gives  Uredo  lumjnata 
as  found  in  Asiatic  Siberia. 

Tranzschel,  1892,  St.  Petersburg  Naturforscher  Gesellschaft  (Bot.  Section),  gives 
preliminary  report  on  producing  P.  Peckiana  by  means  of  artificial  infection  of 
R.  saxatilis  with  spores  of  C.  interstitiale  (C.  nitens). 

1893,  Hedwigia,  H.  V.,  p.  257,  gives  further  successful  results  of  artificial  infec- 
tion, and  concludes  that  the  Caeoma  and  the  Puccinia  must  hereafter  be  known 
as  stages  of  Puccinia  interstitiale  (Schl.) 

Trelease,  1884,  Extract  from  Trans.  Wis.  Academy  of  Science,  Arts  and  Letters, 
V.  VI,  p.  30  gives  host  of  C.  nitens  in  Wisconsin.  •  Probably  the  first  to  call 
this  fungus  Caeoma  nitens. 

1884.  Psyche,   V.  IV,  p.  195,  notes  insect  larvae  as  eating  spores  of  C.  nitens. 
Underwood  &  Cook,  1889,  Illustr.  Fungi,  51,  give  C.  nitens. 

Watt,"  1885,  Canadian  Naturalist  and  Geologist,  Second  Series,  V.  II,  p.  391,  gives 
Ae.  laminatum,  the  specific  term  probably  being  "luminatum"  misspelled. 

Webber,  1889,  Extract  from  Rep.  Neb.  Slate  Board  of  Agr.,  p.  73,  notes  Uredo  (C.) 
nitens  as  being  very  destructive. 

1889,  Neb.  Agr.  Ex.  Sta.,  Bull.  No.  n,  lists  same  on  p.  65, and  Pond  mentions  it 
on  p.  89. 

Winter,  1884,  Rabenhorst's  Kryptogamen  Flora  I-I,  p.  230,  gives  Karsten's(i879)  de- 
scription of  I  stage  of  Ph.  Rubi,  although  he  states  that  he  has  never  seen  the 
same  for  certain. 

1885,  Hedwigia,  B.  XXIV,  p.  181,  gives  C.  nitens  on  R.  villosus  and  R.  Cana- 
densis,  as  sent  from  Missouri  by  Demetrio. 

1885,  Rabenhorst's  Fungi  Europaei,  C.  XXXIII,  n.  3225,  presents  specimens 
of  C.  nitens  for  America  and  Fennia,  and  says  that  Fennia  specimens  are  C. 
nitens  rather  than  a  form  of  Ph.  Rubi  for  which  they  were  sent  to  him. 

G.  P.  CLINTON,  B.S.,  Assistant  Botanist. 


296  BULLETIN  NO.   29.  [December, 

EXPLANATION  OF  PLATES. 

Plate  i.     Fig.  i.     Under  surface  of  blackberry  leaf  thickly  covered  with  sori  of  aecid- 

ium  stage. 

Fig.  2.     Under  surface  of  raspberry  leaflet,  with  both  aecidio-  and  teleuto-sori. 
Fig.  3.     Under  surface  of  blackberry  leaflet,  with  teleutosori  in  groups. 
Fig.  4.     Upper  surface  of  raspberry  leaflet,  with  peculiar  mottled   appearance 

frequently  caused  by  teleutostage  of  fungus. 
Fig.  5.     Cross  section  of  blackberry  leaflet  through  a  sorus  of  the  aecidium 

stage. 
Plate  2.     Fig  i.     Cross  section  showing  part  of  blackberry  leaflet  with  a  sperma- 

gonium  beginning  to  form  just  beneath  the  epidermis. 
Fig.  2.     Slightly  more  advanced  stage. 
Fig.  3.     Mature  spermagonium  in  cross  section. 
Plate  3.     Fig.  1-4.     Haustoria  in  pith  of  very  young  shoot  of  blackberry,  as  seen  in 

cross  section.     2  and  3  show  the  peculiar  conjugation  sometimes  found. 
Fig-  5-7.     Haustoria    in    pith  of  old  blackberry  stems,    in    cross  section,  5 

and  6  being  more  highly  magnified  than  7. 
Fig.  8-9.     Mycelium  in  longitudinal  sections  of  blackberry  pith,  8  being  from 

a  young  and  9  from  an  old  cane. 
Fig  10.     Section  with  mycelium  and   a   haustorium  in  parenchyma  tissue  of 

very  young  leaf. 

Fig.  11-13      Cross  section  of  parenchyma  cells  in  cortex  of  root,   with  mycel- 
ium of  fungus,  ii  showing  cross  end  of  mycleium  between  the  cells,  12  and 

13  haustoria. 
Fig.  14.     Tangential  section  with  mycelium  and  a  haustorium  in  parenchyma 

cells  of  root  cortex. 
Plate  4.     Fig.  1-21.     Aecidiospores  germinating  in  water. 

Fig.  1-7.     Germination  of  same  spore  at  end  of  4,  5,  6,  7,   8,   9,  and  24  hours. 
Fig.  8-12.     Germination  of  spores  during  first  two  days,  and  13  during  third 

day. 
Fig.  14-18.     Spores  from  raspberry,  having  been  48  hours  in  water,   while  19- 

20  show  quicker  germination  at  end  of  24  hours. 
Fig.  21.     Peculiar  tips  of  germ  tubes,  two  showing  suddenly  enlarged  tips,  and 

three  flexuous  tips. 
Fig.  22.     Aecidiospores  that  were  placed  on  lower  moist  surface  of  blackberry 

leaf,  showing  contracted  tip  of  germ  tube,  and  method  of  entrance  through 

stomates. 

Fig.  23.     Peculiar  branch  of  germ  tube  of  a  spore  sown  on  blackberry  leaf. 
Fig.  24-29.     Teleutospores  germinated  in  water,  at  end  of  eight  days.    24,    26, 

28,  29,  optical  sections  of  the  spores,  showing  how  germ  tube  penetrates  the 

exospore. 
Fig.  30.     Mycelium  as  seen  beneath  epidermis,   and  between  guard  cells  of 

stomates.     From  blackberry  leaflet  just  beginning  to  show  teleutoform. 


1893- J        ORANGE  RUST  IN  RASPBEKK1ES   AXD  BLACKBERRIES.  297 

PLATC    / 


298 


BULLETIN   NO.   29.  [December, 

PLATLU. 


1 


1893']        ORANGE   RUST   IN   RASPBERRIES  AND  BLACKBERRIES.  299 

PLATEffl 


joo 


BULLETIN   NO.  29.  [December,  1893.] 


*A  NEW  FACTOR  IN  ECONOMIC  AGRICULTURE. 

Economic  agriculture  has  in  store  many  problems  whose  solution 
will  greatly  lessen  labor  while  at  the  same  time  increasing  the 
productiveness  of  the  soil.  There  is  no  subject  of  greater  interest  and 
importance  to  physiological  botany  and  agriculture  than  the  recently 
discovered  symbiotic  relation  between  different  organisms;  a  relation 
mutually  beneficial  and  in  many  cases  absolutely  necessary  to  existence. 
It  is  the  purpose  of  this  paper  to  discuss  a  form  of  symbiosis  which  may 
prove  to  be  of  special  interest  to  agriculture.  Taking  it  for  granted  that 
most  readers  of  these  bulletins  are  practically  unacquainted  with 
the  subject  "  Symbiosis,"  a  condensed  historical  review  of  it  from  its 
beginning  will  be  first  given. 


[*It  has  been  well  known  for  many  years  that  clover,  especially  when  plowed 
under,  made  a  very  marked  contribution  to  the  fertility  of  the  soil  upon  which  it 
grew,  and  later  scientific  investigations  have  shown  that  this  plant,  and  some  other 
allied  ones,  have  the  peculiarity  of  making  use  of  the  free  nitrogen  of  the  air  as  an 
element  in  their  nutrition.  Most  other  plants  cannot  do  this,  though  all  must  have 
nitrogen  as  a  food  ingredient.  It  is  usually  taken  from  the  soil  in  combination  with 
other  elements;  as,  for  instance,  in  the  lime  forming  nitrate  of  lime.  Now  four-fifths 
of  the  atmosphere  is  free  nitrogen.  If  by  any  means  plants  can  make  use  of  it  as  food, 
they  have  an  abundant  and  constant  supply  at  hand  and  the  combined  form  in  the 
soil  then  becomes  less  important,  or  unnecessary.  Since  the  latter  is  the  most  expen- 
sive of  artificial  fertilizers  and  its  application  is  often  demanded  for  full  crops,  any 
substitute  for  it  must  be  of  immense  practical  value. 

It  has  now  been  shown  that  clover,  like  other  agricultural  plants,  is  of  itself  in- 
capable of  utilizing  free  nitrogen,  but  that  it  does  so  through  the  agency  of  low  organ- 
isms (bacteria)  found  in  little  knots  or  tubercles  which  form  like  galls  upon  the  roots. 
Such  tubercles  are  found  on  the  roots  of  all  plants  which  are  known  to  gain  nutri- 
tion from  free  nitrogen  and  are  not  so  found  upon  any  other  plants.  They  a/te  not 
found  upon  the  roots  of  any  of  the  grasses  or  cereals.  Can  the  organisms  be  made  to 
grow  upon  these  roots  by  any  artificial  means? 

It  must  be  confessed  that  it  would  have  been  exceedingly  hazardous  for  any  one 
to  have  expressed  an  affirmative  opinion  upon  this  question;  but  the  vast  importance 
of  the  matter  made  it  desirable  to  try  anything  which  gave  the  least  promise  of  success. 
In  this  condition  of  things  it  came  to  the  knowledge  of  officers  of  this  Experiment 
Station  that  Dr.  Albert  Schneider,  then  of  Minneapolis,  Minn.,  had  found  from  some 
preliminary  investigations  indications  of  the  possibility  of  adapting  the  organisms  by 
artificial  cultivation  to  growth  upon  the  roots  of  maize  or  of  other  cereals.  He  was 
therefore  secured  to  continue  these  investigations  during  the  latter  part  of  the  sum- 
mer of  1893,  and  was  given  all  the  facilities  at  the  command  of  the  Station.  The 
following  from  his  pen  gives  the  results  as  far  as  obtained.  While  little  direct  evi- 
dence has  been  gained  in  favor  of  ultimate  success,  it  is  considered  desirable  to  pub- 
lish an  account  of  the  work  so  far  done  with  the  hope  of  being  able  at  some  future 
time  to  add  greatly  to  the  information  now  obtained.  The  report  is  necessarily  tech- 
nical in  form  and  several  terms  are  employed  that  may  be  new  to  many  who  read  these 
pages;  but  the  subject  matter  is  also  new  to  the  public  and  other  wording  could 
scarcely  make  it  easier  to  comprehend.  The  term  symbiosis  is  applied  to  the  associa- 
tion of  two  different  kinds  of  living  plants  or  animals  in  a  mutually  helpful  relation. 

THOMAS  J.  BURRILL,   Horticulturist  and  Botanist.] 

301 


302  BULLETIN  NO.   29.  [December, 

BRIEF  HISTORICAL  REVIEW. 

The  term  symbiosis  was  first  used  by  de  Bary  in  1879  *n  an  article 
entitled,  Die  Erscheinung  der  Symbiose.  By  it  he  meant  that  kind  of 
commensalism  or  consortism  between  different  organisms  which  proved 
mutually  beneficial.  In  parasitism  the  benefit  is  always  one-sided,  one 
organism  flourishing  at  the  expense  of  the  other.  The  most  familiar 
form  of  symbiosis  is  to  be  found  in  the  case  of  lichens.  Here  we  find 
an  ordinary  hyphal  fungus  living  in  vital  relation  with  a  filamentous  or 
single-celled  alga.  The  chlorophyll  bearing  algae  make  it  possible  for 
the  fungus  to  develop  on  rocks  and  tree  trunks  where  it  could  not  exist 
alone.  In  turn  the  alga  absorbs  nourishment  from  the  fungus.  It  is 
only  a  few  years  since  the  algae  of  lichens  were  looked  upon  as  spores 
and  hence  named  gonidia.  The  dual  nature  of  lichens  has  been  demon- 
strated both  by  analysis  and  synthesis.  The  algal  and  fungal  portions 
of  a  given  lichen  have  been  separated  and  each  found  to  be  capable  of 
existing  alone.  It  has  been  found  that  by  placing  a  certain  fungus  and 
alga  together  they  form  a  true  lichen. 

A  form  of  symbiosis  of  much  greater  importance  is  to  be  found  with 
certain  forest  trees.  Often  the  greater  portion  of  nourishment  is 
supplied  by  fungi.  These  fungi  stand  in  symbiotic  relation  with  the 
small  rootlets  of  the  tree  forming  a  structure  part  root  and  part  fungus, 
called  a  Mycorhiza.  According  to  the  researches  of  Frank  the  sig- 
nificance of  this  root  symbiosis  is  to  be  explained  as  follows:  The  tree 
as  well  as  the  fungus  requires  humus;  but  the  humus,  before  it  can  be 
readily  taken  up  as  food  by  the  trees,  must  first  be  assimilated  by  the 
fungus.  Frank  and  his  pupil  Schlicht  have  found  symbiotic  fungi 
among  Ericaceae,  Epadridiae,  Empetraceae,  and  Orchidaceae. 

Among  the  Leguminosae  we  meet  still  another  form  of  symbiosis. 
Here  one  of  the  symbionts  is  a  bacterium  (Rhizobium)  and  is  always 
to  be  found  within  the  tissue  of  the  host  forming  swellings  called  tuber- 
cles. The  history  of  Rhizobia  tubercles  is  very  interesting  and  has  led 
to  many  controversies. 

The  tubercles  on  the  roots  of  Leguminosae  had  been  noted  as  early 
as  1852,  though  no  one  understood  their  meaning.  Malpighi  considered 
them  as  galls;  de  Condolle,  as  pathological  growths.  Clos  looked  upon 
them  as  lenticular  growths,  while  Treviranus,  considered  them  undevel- 
oped buds.  Eriksson  gave  a  more  complete  description  of  the  tuber- 
cles of  Faba  vulgar  is.  In  1866  Woronin  noticed  that  the  soft  paren- 
chymatous  cells  of  the  interior  of  the  tubercles  were  entirely  filled  with 
small  bodies.  He  pronounced  these  bacteria.  Most  botanists  coincided 
with  Woronin  as  to  the  bacterial  nature  of  the  tubercle  contents.  These 
bacteria  were  looked  upon  as  true  parasites.  In  1879  Frank  pointed  out 
that  it  was  not  an  ordinary  form  of  parasitism.  In  1887  Hellriegel  con- 
cluded a  series  of  experiments  which  led  him  to  the  conclusion  that  there 
was  some  close  relation  between  the  root  tubercles  of  Leguminosae  and 


1893-]  A  NEW   FACTOR  IN   ECONOMIC  AGRICULTURE.  303 

free  nitrogen  assimilation.  Beginning  with  1885  and  ending  in  1891,  a 
heated  controversy  was  kept  up  concerning  the  contents  of  the  infected 
cells  of  tubercles.  Heretofore  they  had  been  looked  upon  as  bacteria. 
Brunchorst  and  Tschirch  conducted  a  series  of  experiments  in  Frank's 
institute  which  led  them  to  believe  that  the  bacteria,  so-called,  were  not 
bacteria  but  were  bacteroid  bodies  formed  by  the  plants  themselves; 
that  is,  the  bacteria-like  particles  were  albuminous  reserve  products 
which  were  finally  absorbed  by  the  plant  and  utilized  in  maturing  the 
seed.  Frank  readily  seconded  these  conclusions.  Brunchorst  named 
these  bacteria-like  albuminous  substances  Bakteroiden. 

Eriksson  had  already  noted  in  some  tubercles  peculiar  hyphal 
structures  penetrating  the  tubercle.  He  asserts  that  these  hyphae  end 
in  the  meristem  of  the  tubercle  and  that  the  Bakteroiden  bud  off  from 
them  within  the  vegetable  cell.  In  1887  Marshall  Ward  made  a  special 
study  of  the  mode  of  infection  in  Vicia  Faba.  His  observations  coin- 
cided quite  closely  with  those  of  Eriksson.  The  above  mentioned  hyphal 
structures  Ward  looked  upon  as  true  hyphae  of  a  fungus  belonging  to 
the  Ustilagineae.  The  Bakteroiden  he  considered  as  the  spores.  Ac- 
cording to  Vuillemin  the  Bakteroiden  are  simply  differentiations  of  the 
cell  protoplasm  and  the  hyphal  structures  are  to  be  looked  upon  as  the 
tubercle  producing  organism.  He  maintains  that  he  succeeded  in  stain- 
ing a  cell  membrane  and  hence  called  it  a  true  hyphal  fungus  belonging 
to  the  Chytridiaceae,  naming  it  Cladochytrium  leguminosarum.  Beyer- 
inck  looked  upon  these  hyphal  structures  as  mere  Schleimfaden,  produced 
by  the  plant  cells  themselves.  He  supposed  them  to  be  formed  from 
the  remnants  of  spindle  threads  left  after  nuclear  division  had  taken 
place.  Relying  upon  this  assumption  he  also  endeavored  to  explain  the 
fact  that  the  Schleimfaden  pass  directly  through  the  cell  wall.  The 
Bakteroiden  Beyerinck  considered  the  infecting  organisms,  formed 
from  the  microsomatic  bodies  found  in  the  meristem  cells  of  the  tuber- 
cles. The  microsomatic  bodies  were  looked  upon  as  bacteria  which 
normally  live  within  the  soil  but  which  are  enabled  to  enter  the  plant 
root  in  some  unknown  way.  He  also  seconded  Brunchorst's  and  Frank's 
conclusions  that  the  Bakteroiden  are  re-absorbed  by  the  plant.  Prazmowski 
looked  upon  the  hyphal  structure  as  a  plasmodium  filled  with  bacilli- 
like  organisms.  As  soon  as  these  enter  the  root  parenchyma  the  plas- 
modium surrounds  the  cell  protoplasm  so  that  cell  protoplasm,  plas- 
modium, and  the  bacilli-like  bodies  form  a  thorough  mixture.  Here  the 
bacilli-like  bodies  are  converted  into  the  Bakteroiden.  Later  Prazmowski 
changes  his  opinion,  maintaining  that  the  plasmodium  is  a  hyphae-like 
tube  filled  with  bacteria.  The  spores  of  the  bacteria  enter  the  root 
hairs  in  some  way  and  multiply  enormously.  The  bacteria  tube  pushes 
forward  as  far  as  the  meristem  of  the  tubercle  where  it  dissolves  and 
liberates  the  bacteria;  the  latter  become  mixed  with  the  cell  protoplasm, 
and  are  finally  converted  into  the  peculiar  Bakteroiden.  Schroeter  con- 
sidered the  hyphal  structures  as  true  plasmodia  of  a  fungus  belonging  to 


304  BULLETIN  NO.  29.  \JDecember, 

the  Myxomycetes.  This  fungus  he  named  Phytomyxa  leguminosarum. 
Frank  came  to  the  conclusion  that  the  hyphal  structures  were  products 
of  the  plant  cells  themselves,  and  served  the  purpose  of  assisting  the 
Rhizobia  into  the  root  parenchyma,  hence  he  named  them  Infek- 
tionsfaden. 

According  to  Frank  infection  takes  place  as  follows:  The  roots  of 
Leguminosae  secrete  a  substance  which  serves  as  an  attraction  to  the 
Rhizobia  in  the  soil.  They  accumulate  and  multiply  on  the  surface  of 
the  root,  some  of  them  enter  the  outer  cells  and  are  then  conducted  into 
the  interior  by  the  Infcktionsfdden.  Here  the  Rhizobium  assimilates 
the  cell  protoplasm  and  becomes  much  changed  in  form,  finally  becom- 
ing converted  into  Bakteroiden.  In  1890  he  believed  with  Brunchorst 
that  the  Bakteroiden  were  albuminoid  bodies  formed  from  the  cell  proto- 
plasm, in  which  the  Rhizobia  were  imbedded.  In  1891  he  changes  his 
opinion  in  regard  to  Bakteroiden  maintaining  that  they  are  true  bacteria, 
as  stated  above. 

So  far  Frank  adheres  to  the  opinion  that  there  is  but  one  species  of 
Rhizobium,  namely:  Rhizobium  leguminosarum.  Investigations  by 
the  writer  have  led  to  the  belief  that  there  are  at  least  several  species. 
One  and  the  same  species  may  be  found  on  different  plants.  For 
example,  one  species,  designated  Rhizobium  curvum,  was  noticed  on 
Phaseolus  pauciflorisj  another,  Rhizobium  mutabile,  was  found  on 
Tri folium  pratense  and  Tri  folium  repens,  on  Melilotus  alba  and 
Medicago  sativa.  The  much  discussed  Infektionsfaden  seem  to  bear 
an  incidental  relation  only  to  the  Rhizobia.  It  is  not  probable  that  the 
roots  of  Leguminosae  secrete  or  excrete  a  substance  that  is  attractive  to 
Rhizobia.  All  later  experiments,  as  far  as  known,  verify  these  state- 
ments. Rhizobia  in  some  way  gain  access  to  the  surface  cells  of  the 
roots  and  multiply  and  produce  their  peculiar  changes  in  plant  economy. 
Elsewhere  the  writer  has  described  the  root  tubercle  morphology  and 
hence  will  not  take  up  space  here.  It  should  be  said,  however,  that  the 
root  tubercles  are  quite  permanent  in  structure;  and  that  it  does  not 
seem  to  the  writer  that  the  contents  of  Rhizobia  and  tubercles  are  at 
any  time  directly  reabsorbed  by  the  plant. 

It  would  be  impossible  to  review  all  the  work  that  has  been  done 
in  regard  to  the  root  tubercles  and  the  free  nitrogen  assimilating 
Rhizobia  they  contain.  Carefully  considered  and  weighed,  the  dis- 
cussions and  controversies  up  to  date  may  be  summarized  as  follows: 

1.  Certain  bacteria,  called  Rhizobia,  live  in  symbiotic  or  mutually 
beneficial   relations  with  certain   higher  plants,  especially  the  Legumi- 
nosae. 

2.  Plants   can  develop  without  these   Rhizobia,    but,   as   a    rule, 
thrive  much  better  with  them. 

3.  These  Rhizobia  have  the  power  of  assimilating  for  the  use  of 
the  plant  the  free  nitrogen  of  the  air. 

4.  There  are  several  species  of  Rhizobia. 


1893*]  A  NEW  FACTOR   IN  ECONOMIC  AGRICULTURE.  305 

5.  Rhizobium  mutabile  very  likely  stands  preeminent  in  the  nitro- 
gen assimilating  function. 

6.  The  Infektionsfaden  probably  have  no  essential  relation  to  the 
Rhizobia. 

7.  The  tubercles  are  abnormal  growths  produced  by  the  presence 
of  the  Rhizobia. 

8.  The  tubercles  have  a  definite  structure  and  form  a  permanent, 
coherent  part  of  the  root. 

9.  The  Bakteroiden  of  Brunchorst  (Rhizobia  mutabile)  are  capable 
of  being  cultivated  in  suitable  media. 

PLAN    OF    RESEARCH. 

The  plan,  though  in  a  certain  sense  original,  did  not  suggest  itself 
spontaneously,  but  is  the  result  of  careful  study. 

That  the  Rhizobia  play  an  important  part  in  the  vegetable  king- 
dom is  definitely  settled.  The  results  of  Hellriegel's,  Willf  arth's,  Lawes 
and  Gilbert's,  and  Frank's  experiments  have  opened  a  new  era  in 
economic  agriculture.  They  have  begun  a  work  which  will  doubtless 
result  in  some  great  good. 

Several  interesting  problems  suggest  themselves  for  solution.  One, 
to  which  attention  is  here  directed,  is  to  ascertain  if  the  Rhizobia  of 
Leguminosae  can  be  induced  to  live  in  symbiotic  relation  with  plants  of 
other  families,  as,  for  example,  the  Gramineae.  If,  for  instance,  the 
Rhizobium  of  the  Melilotus  alba  root  can  be  transplanted  to  the  Zea 
Mays  root  and  there  continue  its  nitrogen-assimilating  function,  then  our 
corn  crop  can  be  doubled  and  trebled  with  the  same  amount  of  labor 
now  expended  on  an  average  crop.  Of  course  it  must  be  left  for  the 
future  to  decide  whether  this  can  be  done.  So  far  as  known  no  experi- 
ments have  as  yet  been  attempted  in  this  line.  Knowledge  of  Rhizobia 
and  bacteria  in  general  leads  to  the  belief*  that  satisfactory  results  may 
be  obtained.  A  brief  outline  of  the  plan  of  research  which  suggests 
itself  is  as  follows: 

1.  To  make  a  suitable  culture  medium. 

2.  To  develop  Rhizobia  in  this  culture  medium. 

3.  To  change  the  culture  medium  by  degrees  from  a  leguminous 
nature  to  a  gramineous  nature. 

4  To  modify  the  Rhizobia  by  successively  transferring  from  a 
highly  leguminous  medium  to  a  highly  gramineous  medium. 

5.  To  inoculate  Gramineae  with  modified  Rhizobia. 

6.  Life  history  of  Rhizobia. 

First,  to  make  a  suitable  culture  medium.  Naturally,  in  order  to 
induce  the  Rhizobia  to  develop  outside  of  roots,  there  must  be  sup- 
plied artificially  conditions  approaching  those  of  nature.  Rhizobia,  as 
they  are  found  in  root  tubercles,  are  placed  under  the  following  con- 
ditions: i.  They  are  in  a  vegetable  medium.  2.  The  medium  is 
slightly  acid  in  reaction.  3.  They  are  not  exposed  to  light.  Artificially, 


306  BULLETIN  NO.  29.  [December, 

these  conditions  can  be  supplied  as  follows:  Instead  of  using  the  ordin- 
ary gelatine-peptone  bouillon  the  purpose  is  to  prepare  a  special  culture 
medium  from  agar-agar  and  a  water  extract  of  certain  leguminous  roots, 
which  is  then  made  slightly  acid  in  reaction  and  placed  in  the  dark  after 
being  inoculated  with  a  given  species  of  Rhizobium.  By  this  means  all 
the  above  mentioned  essential  conditions  are  met  with.  Frank's  (as 
well  as  those  of  others)  failures  to  make  cultures  of  the  so  called 
Bakteroiden  were  probably  due  to  the  fact  that  he  did  not  supply  the 
required  conditions.  Frank  used  gelatine-peptone  bouillon.  He  neither 
mentions  the  reaction  nor  the  light  conditions.  The  writer  attempted 
cultures  in  both  gelatine-peptone  and  agar-agar  bouillon,  slightly  alkaline 
in  reaction  and  placed  in  the  dark  after  being  inoculated.  Bakteroiden 
(Rhizobium  mutibile)  were  not  thus  developed,  but  there  was  readily 
obtained  a  culture  of  Rhizobiam  Frankii,  var.  ma/us.  Recently  Atkin- 
son has  succeeded  in  cultivating  the  Bakteroiden  of  vetch  in  an  agar-agar 
peptone-vetch  culture,  which  demonstrates  conclusively  that  the 
Bakteroiden  are  true  bacteria.  The  plan  of  the  writer  is  to  modify 
somewhat  Atkinson's  culture  medium,  and  to  omit  the  peptone  which  is 
an  animal  product.  Instead  of  making  an  extract  of  the  entire  plant, 
roots  only  will  be  used.  Atkinson  does  not  state  the  reaction  of  his 
culture  media,  though  it  is  to  be  supposed  that  they  were  acid,  as  vegetable 
cell  sap  is  normally  acid.  Presumably  he  kept  his  cultures  in  diffused 
light,  as  he  does  not  mention  anything  to  the  contrary.  There  would 
seem  to  be  but  little  difficulty  in  preparing  a  suitable  culture  medium  in 
which  to  develop  Rhizobia. 

The  second  step  is,  to  develop  Rhizobia  in  this  special  culture 
medium.  The  desire  is  to  cultivate  Rhizobium  mutabile  {Bakteroiden  of 
Brunch.),  as  it  is  believed  to  be  the  one  which  has,  preeminently,  the 
power  to  assimilate  free  nitrogen.  Since  Atkinson  has  demonstrated 
that  it  can  be  cultivated,  no  doubts  need  be  entertained  on  that  score. 
All  that  is  required  is  to  place  it  in  the  proper  medium  under  antiseptic 
precautions.  Being  once  assured  of  a  pure  culture  of  Rhizobium  muta- 
bile, considerable  progress  is  made  toward  the  solution  of  the  problem 
under  consideration. 

The  third  step,  to  change  the  culture  medium  by  degrees  from  a 
leguminous  nature  to  a  gramineous  nature,  is  of  great  importance.  It  is 
a  well  known  fact  that  low  organisms,  especially  bacteria,  may  become 
modified  so  as  to  adapt  themselves  to  environments  which  proved  fatal 
before  they  were  thus  modified.  The  purpose  is  to  change  the  culture 
media  so  as  to  induce  the  Rhizobia  to  become  modified.  The  plan  is  as 
follows:  To  make  culture  media  in  which  the  agar-agar  is  present  in  a 
constant  percentage  and  the  vegetable  extracts  variable.  As  already  in- 
dicated the  plan  is  to  modify  Rhizobia  of  a  given  leguminous  plant  so 
as  to  be  capable  of  transplanting  to  the  roots  of  a  given  gramineous 
plant.  To  begin  with  a  culture  medium  will  be  taken  which  contains  the 
fixed  quantity  of  agar-agar  and  100  per  cent  of  extract  of  Melilotus 


1893-]  A   NEW  FACTOR   IN  ECONOMIC   AGRICULTURE.  307 

roots;  the  culture  medium  next  in  the  series  shall  contain  80  per  cent 
Melilotus  root  extract  and  20  per  cent  of  Zea  Mays  root  extract;  the  next 
in  the  series  shall  contain  60  per  cent  of  Melilotus  extract  and  40  per 
cent  of  Zea  extract  and  so  on,  each  of  the  series  differing  by  20  per 
cent  in  the  relative  amounts  of  sweet  clover  and  corn  root  extracts.  At 
one  end  of  the  series  is  a  culture  containing  100  per  cent  of  Melilotus 
alba  root  extract;  at  the  other  end,  a  culture  containing  100  per  cent 
Zea  Mays  root  extract. 

The  fourth  step  explains  itself  from  what  has  already  been  stated. 
The  Rhizobia  are  to  be  transferred  from  one  culture  medium  to  another 
until  they  have  passed  through  the  series.  By  that  time  they  are  sup- 
posed to  have  become  modified  to  such  an  extent  as  to  grow  and  multi- 
ply in  roots  of  corn. 

This  is  to  be  attempted  in  the  fifth  step,  to  inoculate  Gramineae 
with  modified  Rhizobia.  The  inoculation  must  be  conducted  with  great 
care.  Plants  to  be  experimented  upon  should  be  placed  in  special  glass 
jars.  In  place  of  soil,  quartz  sand  will  be  used  with  culture  solution. 
Plants  must  be  grown  in  a  medium  which  can  be  made  perfectly  sterile. 
The  modified  Rhizobia  are  to  be  transferred  from  the  culture  to  the 
vessel  containing  the  sterilized  corn  plants. 

Lastly,  the  behavior  of  Rhizobia,  will  be  carefully  noted  and  their 
life  history  more  carefully  studied.  Their  behavior  under  normal  and 
abnormal  surroundings  will  be  observed.  Though  present  knowledge 
concerning  the  life  history  of  Rhizobia  warrants  undertaking  the  experi- 
ments just  outlined,  yet  it  is  quite  essential  that  their  life  history 
should  be  more  thoroughly  studied,  especially  in  regard  to  the  following 
conditions: 

1.  Temperature. — (a)  Minimum.     (b)  Optimum,     (f)  Maximum. 

2.  Light. — (a)  Darkness,     (b)  Semi-darkness,     (c)  Green,      (d)  Blue.      (/)  Red. 
(/)  Yellow,     (g)  White  light  (diffused),     (h)  White  light  (direct). 

3.  Moisture. — (a)  Very  dry.     (b)  Moderately  moist,     (c)  Very  moist. 

4.  Atmospheric  Pressure. — (a)  High  pressure,     (b)  Low  pressure. 

5.  Heliotropism. — 

6.  Hydrotropism. — 

7.  Geotropism. — 

These  experiments  are  not  undertaken  with  any  desire  to  magnify 
unduly  the  importance  of  bacteria,  nor  with  absolute  confidence  of  suc- 
cess. As  already  stated,  the  present  knowledge  of  Rhizobia  and  bac- 
teria in  general  justifies  undertaking  these  experiments. 

RESEARCH. 

The  first  thing  was  to  prepare  suitable  culture  media  in  which  to 
grow  Rhizobia.  For  this  purpose  two  aqueous  extracts  were  made  from 
Melilotus  alba,  one  from  the  roots,  rootlets,  and  tubercles ;  the  other  from 
the  upper  portions  of  stems  and  leaves.  They  were  prepared  in  the 
following  manner:  About  one-half  a  kilogram  of  roots  and  rootlets 
were  weighed,  carefully  washed,  then  finely  chopped,  and  put  in  a  jar 
with  one  liter  of  distilled  water.  This  was  allowed  to  stand  in  a  cool 


308  BULLETIN  NO.  29.  [December, 

place  for  twenty-four  hours,  being  shaken  occasionally.  The  juice  was 
then  squeezed  out  through  cloth  into  a  beaker,  and  ten  grams  of  agar 
were  added.  After  standing  for  twelve  hours  the  whole  was  heated  to 
near  the  boiling  point  until  the  agar  was  dissolved.  It  was  then  filtered 
through  coarse  filter  paper  in  a  hot  water  filter.  The  agar  extract 
medium  of  stems  and  leaves  was  prepared  in  a  similar  way.  To  por- 
tions of  these  filtered  media  were  added  peptonum,  pancreatin,  and  salt 
in  various  proportions.  Some  neutral  and  slightly  alkaline  media  were 
made  by  the  addition  of  sodium  carbonate  solution.  Litmus  paper  tests 
showed  that  the  normal  extracts  of  Melilotus  roots  and  stems  were  acid 
in  reaction,  the  latter  more  highly  than  the  former.  These  various  cul- 
ture media  were  now  ready  for  use. 

Next,  plants  of  Melilotus  alba  with  normal,  fully  formed  root  tuber- 
cles were  secured.  The  tubercles  were  removed,  washed  in  distilled 
water,  and  quickly  dried  with  blotting  paper  which  had  been 
passed  through  the  flame  of  a  Bunsen  burner.  The  tubercle  was  then 
passed  through  the  flame  and  cut  with  a  sharp,  sterilized  knife,  care 
being  taken  not  to  allow  the  knife  blade  to  drag  over  the  cut  surface. 
Test  tubes  with  culture  media  were  then  inoculated  from  the  cut  sur- 
face by  means  of  a  platinum  needle.  These  inoculated  test  tubes, 
numbering  about  fifty,  were  set  aside  in  a  dark  chamber  at  the  normal 
summer  temperature  of  the  room.  In  about  four  or  five  days  a  whitish 
growth  was  noticed  in  most  tubes  containing  agar  extract  of  Melilotus 
roots.  Examination  under  a  medium  power  showed  that  they  consisted 
of  organisms  resembling  in  size  and  form  Rhizobium  Frankii,  var.  majus. 
They  were  somewhat  smaller,  end  spores  less  distinct,  and  the  majority 
were  motile  during  their  early  life  history.  They  multiplied  from 
spores  as  well  as  by  transverse  division.  Their  motility  was  especially 
noticeable  in  liquid  media,  often  when  of  quite  mature  growth.  Some- 
times two  or  even  more  which  had  just  completed  division  moved  about 
with  great  rapidity.  Their  manner  of  movement  led  to  the  supposition 
that  they  possessed  cilia.  Staining  heavily  with  Hoffman's  violet  and 
examining  under  a  Zeiss' homogeneous  immersion  objective  demonstrated 
the  presence  of  cilia.  Each  motile  organism  generally  possessed  two 
cilia,  one  at  either  end,  sometimes  only  one.  Spores  just  beginning  de- 
velopment sometimes  had  as  many  as  three  or  four. 

Tubes  containing  culture  medium  (acid )  of  stems  and  leaves  of 
Melilotus  showed  no  development  of  any  kind  for  eight  or  ten  days, 
when  a  small  glistening  colorless  growth  was  noticed  in  several  of  them. 
Examination  showed  the  presence  of  much  modified  Rhizobiummutabile. 
(Plate  III,  5.)  Cultures  renewed  from  these  tubes  produced  no 
further  developments.  In  fact  all  growth  ceased  shortly  in  all  tubes 
containing  the  extract  of  stems  and  leaves.  The  medium  was  no  doubt 
too  acid  in  reaction.  Further  efforts  with  various  acid  and  alkaline 
media  to  secure  pure  cultures  of  Rhizobium  mutabile  were  apparently 


1893-]  A  NEW  FACTOR  IN  ECONOMIC  AGRICULTURE.  309 

unsuccessful.     Careful  examinations  of  tubercles  and   cultures  obtained 
from  them  finally  led  to  the  following  conclusions: 

Tubercles  of  Melilotus  alba  contain  two  predominating  types  of 
Rhizobia,  namely,  Rhizobium  Mutabile  and  the  above  described  motile 
forms.  These  motile  forms  develop  much  more  readily  and  by  their 
great  numbers  prevent  the  subsequent  development  of  Rhizobium  muta- 
bile.  In  the  living  plant  cells  the  motile  Rhizobia  are  found  in  the 
Infcktionsfaden  of  Frank.  They  develop  first  and  by  their  irritating 
presence  cause  the  development  of  the  Faden  which  now  are  a  means  of 
separating  the  organisms  from  the  other  cell  contents.  This  also  ex- 
plains the  predominating  presence  of  Rhizobia  of  Faden  in  the  meristem 
area  of  the  tubercle.  The  motion  of  these  Rhizobia  is  in  the  direction 
of  their  longer  axis,  hence  the  tubes  {Faderi)  are  produced  in  the  direc- 
tion of  the  greatest  expenditure  of  energy.  As  already  stated  the  irri- 
tation caused  by  their  motion  induces  the  cell  cytoplasm  to  deposit  around 
them  a  coating  of  cellulose  which  gives  the  appearance  of  Faden.  These 
are  found  especially  in  the  meristem  area;  but  since  the  tubercles  grow 
and  the  Faden  are  as  permanent  a  structure  as  the  cell  wall,  they  remain 
as  tubes  containing  spores  and  mature  Rhizobia.  The  Rhizobia  are 
always  found  in  a  position  parallel  to  the  long  axis  of  the  Faden,  ex- 
cept where  those  peculiar  bulgings  and  swellings  occur.  Staining  the 
Faden  with  chlorzinc-iodine  showed  the  presence  of  a  wall  containing 
cellulose.  Placing  them  in  various  culture  media  produced  no  growth 
or  change  of  any  kind ;  but  the  contained  Rhizobia  rapidly  developed 
without  producing  any  continuation  of  the  Faden.  This  demonstrated 
that  the  Rhizobia  were  not  the  cause  of  the  development  of  the  Faden 
and  that  the  Faden  are  not  living  organisms.  After  the  infected  cells 
of  the  tubercle  had  become  more  mature,  the  second  predominating  type 
of  Rhizobium,  namely,  Rhiziobiummutabile,  began  to  develop  and  finally 
filled  the  entire  cell.  Some  tubercles,  especially  the  older  ones  con- 
tain, beside  the  predominating  types,  five  or  six  other  species.  Since 
these  seem  to  be  the  conditions  of  affairs,  it  can  readily  be  understood 
how  difficult  it  would  be  to  obtain  a  pure  culture. 

It  not  being  practicable  to  secure  a  pure  culture  of  Rhizobium  muta- 
bile  of  Melilotus  alba,  the  next  attempt  was  to  secure  a  pure  culture  of 
Rhizobimn  Frankii,  var.  majus,  of  Phaseolus  vulgaris  (garden  bean),  but 
here  much  the  same  difficulty  was  found.  Bean  tubercles  contain  also  the 
above  described  motile  form  {Rhizobium  Frankit)  in  small  numbers.  How- 
ever, in  order  not  to  lose  any  more  time,  and  supposing  that  any  species  of 
Rhizobium  would  serve  much  the  same  purpose  for  these  preliminary 
experiments,  bean  Rhizobia  cultures  were  continued.  They  readily  grew 
upon  bean-agar  extracts  and  also  upon  mixtures  of  corn  and  bean 
extracts.  It  was  supposed  that  they  would  also  grow  in  pure  corn- 
agar  extracts.  The  question  for  solution  was,  How  long  will  it  be 
necessary  to  allow  the  Rhizobia  to  grow  in  corn-agar  extract  until  they 
become  sufficiently  modified  to  develop  in  or  upon  corn  roots?  The 


310  BULLETIN  NO.  29.  [December, 

purpose  in  passing  the  Rhizobia  through  a  series  of  culture  media  made 
from  corn  bean-agar  extracts  was  to  modify  them  gradually,  else  they 
might  finally  die  out,  if  too  long  continued  or  suddenly  transferred  upon 
pure  corn-agar  extract.  Though  the  Rhizobia  developed  upon  pure 
corn  root-agar  extract,  yet  it  was  plainly  seen  that  they  grew  much 
better  in  bean-agar  extracts.  After  the  Rhizobia  were  passed  through 
the  series  of  cultures  they  were  placed  in  pure  corn  root-agar  extract, 
a  transfer  being  made  every  sixth  day. 

In  one  month  from  the  time  cultures  were  begun  upon  the 
pure  corn  extract,  the  first  trial  inoculations  were  made  upon  corn 
and  oats  plants  which  had  been  grown  under  the  following  conditions: 
Lemonade  tumblers  of  heavy  glass  (large  size)  were  obtained.  A  small 
hole  was  drilled  through  the  bottom  of  each  for  drainage  purposes. 
These  were  thoroughly  washed  and  sterilized.  In  the  bottom  of  each 
was  placed  a  plug  of  cotton  followed  by  one- half  a  gill  of  coarse  gravel, 
then  another  plug  of  cotton  followed  by  one-half  a  kilogram  (about 
one  pound)  of  carefully  washed,  tertiary  quartz  sand.  The  sand  in  the 
vessels  was  then  moistened  with  distilled  water.  The  vessels,  with  con- 
tents, were  then  placed  in  a  hot  air  sterilizer  for  two  hours  at  a  tempera- 
ture of  120°  F.  After  the  vessels  were  sufficiently  cool  they  were 
planted  with  sterilized  corn  (white  dent)  and  oats  and  placed  on  a  table 
in  the  laboratory  room.  All  the  seed  planted  came  up  in  about  four 
days.  Some  plants  were  inoculated  as  soon  as  they  appeared  above  the 
sand.  Others  eleven  days  after  sprouting.  Inoculations  were  made  by 
mixing  contents  of  test  tubes  containing  modified  Rhizobia  with  distilled 
water  and  pouring  contents  over  the  sand  near  the  stems  of  the  plants, 
so  as  to  allow  as  much  of  the  fluid  as  possible  to  drain  along  roots  and 
rootlets.  About  twenty  days  after  inoculation  roots  were  washed  and 
examined.  No  tubercles  were  visible.  Inoculated  plants  of  corn  looked 
slightly  more  thrifty  than  those  not  inoculated  and  possessed  more  fine 
rootlets.  No  other  differences  were  visible  to  the  naked  eye.  Micro- 
scopic examination  showed,  furthermore,  that  inoculated  corn  plants 
were  infected  by  Rhizobium  Frankii,  var.  majus.  (Plate  III,  i.)  Infec- 
tion was  by  no  means  general.  Some  of  the  hair  cells  were  infected, 
often  causing  them  to  bulge  at  points  of  infection.  Some  of  the  epiderm- 
al cells  were  infected.  The  most  extensive  infection  took  place  in 
parenchyma  cells  near  the  vicinity  of  secondary  root  formations,  without, 
however,  producing  any  change  in  the  size  and  form  of  the  cells. 
Cells  were  only  partially  filled  with  Rhizobia,  as  seen  in  the  plate. 
Inoculated  corn  plants  also  possessed  more  hair  cells  than  those  not  inoc- 
ulated. No  change  whatever  was  noticeable  in  oat  plants. 

The  reader  will  please  bear  in  mind  that  this  is  a  preliminary  report 
only,  and  that  the  results  of  the  experiments  are  far  from  being  conclu- 
sive. The  following  are,  however,  the  probable  conclusions  from  the 
apparent  results  obtained 


A  NEW  FACTOR   IN   ECONOMIC   AGRICULTURE.  3!  I 

1.  Rhizobia   of   Leguminosae    are    capable   of  being   sufficiently 
modified    to    develop   to    a  certain  extent  in   root   cells   of    corn    (Zea 
Mays). 

2.  Presence  of   modified   Rhizobia   produces    increased    nutritive 
changes  in  corn. 

3.  Presence  of    modified    Rhizobia    (modified    in    corn   root-agar 
extract)  has  no  visible  effect  upon  oats  (A vena  sativa). 

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1893-]  A  NEW   FACTOR  IN  ECONOMIC  AGRICULTURE.  313 

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314  BULLETIN  NO.  29.  [December, 

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1893-]  A   NEW  FACTOR  IN  ECONOMIC   AGRICULTURE.  315 

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Ward,  Ann.  of  Bot.,  1888. 

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*Ward,  Ann.  Sc.  Agron.,  1888. 

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*Warington,  Exp.  Sta.  Record,  U.  S.  Dept.  Agr.,  1892 

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Willfarth,  Beilageh.  z.  Riibenz.  Indus.,  Nov.,  1888. 

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*Willfarth,  Ann.  Agron.,  1888. 

*Willfarth,  Bot.  Centralbl.,  1889. 

*Willfarth,  Chem.  Centralbl.,   1893. 

*Willfarth,  Exp.  Sta.  Record,  U.  S.  Dept.  Agr.,  1893. 

Wittmack,  Verh.  d.  Bot.  Ver.,  Brandenburg,  1874. 

Wolff,  Brand  des  Getreides,  1874. 

Woods,  StorrsAgr.  School,  Bull.  No.  5,  1889, 

Woods,  Storrs  Agr.  School,  Conn.,  p.  44,   Rep't,  1890. 

*Woods,  Exp.  Sta.  Record,  U.  S.  Dept.  Agr.,  1890,   1891,  1892 

Woronin,  Mem.  d.  1'Acad.  d.  Sc.,  No.  6,  1866. 

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*Woronin,  Bot.  Centralbl.,  1889. 

Zopf,  Die  Pilze,  1890. 

ALBERT  SCHNEIDER. 

EXPLANATION  OF  PLATES. 

PLATE  I.— i.  Longitudinal  median  section  of  portion  of  rootlet  and  developing  tubercle 
of  Trifolium  Pratense.  (a)  Normal  hair  cells.  (£)  Hair  cell  infected  by  Rhizo- 
bia.  (c]  Dwarfed  hair  cells  on  tubercle,  (d)  Epidermal  layer.  (e)  Infected 
area  of  tubercle.  Cells  are  enlarged  containing  Rhizobia,  Infektionsfiiden, 
and  abnormally  large  nuclei,  (f)  Infektionsfaden  containing  smaller  Rhizo- 


316  BULLETIN  NO.  29.  [December, 

bia.  (Rhizobium  Frankii?}.  (Left  colorless  in  this  figure),  (g)  Apical  area  of 
tubercle.  Subsequent  development  of  the  tubercle  is  outward  from  this  area. 
(h)  Area  from  which  the  vascular  system  of  the  tubercle  will  arise.  (i)  Vascu- 
lar system  of  rootlet. 

2.  Semidiagramatic  figures  showing  probable  mode  of  the  growth  and  extension  of 

the  Infektionsfdden  in  the  infected  area  of  tubercle. 

I.  Single  cell  from  the  apical  area  of  tubercle,     (a)  The  beginning  of  an  Infek- 
tionsfdden.     It  is  simply  a  group  of   Rhizobia  surrounded  by  a  coating  of 
cellulose  secreted  by  the  cell  cytoplasm,    (b)  Another  group  of  Rhizobia  differ- 
ing from  those  of  (a).  They  freely  mix  with  the  cell  cytoplasm  and  do  not  have  a 
coating   of  cellulose  deposited  around  them.     (Example,    Rhizobium   mutabile.} 
(n)  Neuclus  of  cell. 

II.  Later   stage  of  the  same  cell.     Groups  (a)  and  (&)  are  enlarged.       The  nu- 
cleus has  begun  to  divide. 

III.  Later   stage  than   II.     The   new  cell  wall  (c)  has  begun  to  form,  passing 
through  both  groups  of  Rhizobia. 

IV.  Complete  cell  division.      Two  autoinfected  daughter  cells  have  developed 
from  the   mother  cell.     As  is  seen,  the  Fdden  are  not  of   the   same  thickness 
throughout.     Local  increase  in  the  development  of  Rhizobia  causes  swellings. 
This  is  nearly  always  the  case  next  to  the  new  cell  wall  (III  and  IV). 

V.  Group   of  mature  cells  from   infected   area,     (a)  Infektionsfdden  filled   with 
Rhizobia  (Rhizobium  Frankii?}.    (b]  Rhizobium  mutabile  filling  remaining  portion 
of  cell   and  intimately   mixed  with  cell  cytoplasm  forming  the  mycoplasm  of 
of  Brunchorst  and  Frank. 

3.  Small  portion  of  root  of  Melilotus  alba  with  tubercles,     (a)  Developing  tuber- 
cles,    (b)  Later   stage   showing  dichotomous   mode  of  branching  of   tubercle. 
(c)   Single  mature  tubercles,     (d)  Grape  bunch-like  group  of  tubercles.     Very 
common  with  Melilotus. 

[i  and  2,  highly  magnified;  3  is  natural  size.] 

PLATE  II. — i.  Peculiar  Rhizobia  sparingly  present  in  infected  cells  of  tubercles  of 
Petalostemon  violaceus.  As  a  rule,  each  cell  contains  three  or  four  of  these 
organisms.  • 

2.  Rhizobium  mutabile  of  Trifolium  (clover).        (a)  Spores.       (b}  Developing  spores. 

3.  Rhizobium  mutabile  of  Melilotus  alba  (sweet  clover),     (a)  and  (b}  as  in  2. 

4.  Rhizobium  mutabile  of  Trifolium,  later  stage. 

5.  Rhizobium  curvum  of  Phaseolus  (bean). 

6.  Rhizobium  Frankii,  var.  ma/us,  of  Phaseolus  vulgaris. 

7.  Rhizobium  Frankii  of  Infektionsfaden  of  Melilotus,  Trifolium,  and  other  genera 

of  plants. 

8.  Rhizobium  Frankii,  var.  minus  of  Pisum  (pea)  Infektionsfdden.     (a)   Spores   and 

young  Rhizobia  with  cilia. 

9.  Rhizobium  spheroides  of  Pisum  sativum.  They  often  contain  highly    refracti  ve 

bodies  the  function  of  which  is  undetermined. 

10.  Rhizobium  nodosum  of  Cassia  (partridge  pea). 

[Highly  magnified.] 

PLATE  III. — i.  Longitudinal  section  of  portions  of  inoculated  corn  (Zea  Mays]  rootlet. 
(a)  Hair  cells  infected  by  modified  Rhizobia.  Cells  become  somewhat  enlarged 
at  points  of  infection,  (b)  Parenchyma  cells  infected  by  modified  Rhizobia; 
cells  remain  unchanged,  (c]  Secondary  rootlet. 

2.  Rhizobium  mutabile  cultivated  upon  bean  and  corn  root  extract. 

3.  Rhizobittm  mutabile  cultivated  upon  corn  root  extract. 

4.  Rhizobium  mutabile  cultivated  upon  sweet  clover  root  extract. 

5.  Rhizobium  mutabile  cultivated  upon   sweet  clover  extract  prepared  from  stems 

and  leaves. 

All  culture  media  were  solidified  by  agar-agar. 
[Highly  magnified.] 


1893-]  A  NEW  FACTOR   IN  ECONOMIC  AGRICULTURE. 


3'7 


PLATE! 


3.8 


BULLETIN    NO.    29. 


[  December, 


PLATE  H. 


1893-]  A  NEW  FACTOR  IN  ECONOMIC  AGRICULTURE.  319 


Vt- 


PLATE  I 


320  BULLETIN  NO.  29.  [  December,  1893. ] 


ORGANIZATION. 


BOARD  OF  TRUSTEES  OF  THE  UNIVERSITY  OF  ILLINOIS. 

NELSON  W.  GRAHAM,  Carbondale,  President. 
JOHN  P.  ALTGELD,  Springfield,  Governor  of  Illinois. 
DAVID  GORE,  Springfield,  President  State  Board  of  Agriculture. 
HENRY  RAAB,  Springfield,  Superintendent  Public  Instruction. 
FRANCIS  M.  McKAY,  Chicago.  ALEXANDER  McLEAN,  Macomb. 

SAMUEL  A.  BULLARD,  Springfield.  RICHARD  P.  MORGAN,  Dwight. 

JOHN  H.  BRYANT,  Princeton.  NAPOLEON  B.  MORRISON,  Odin. 

JAMES.  E.  ARMSTRONG,  Chicago.  ISAAC  S.  RAYMOND,  Sidney. 

BOARD  OF  DIRECTION  OF  THE  EXPERIMENT  STATION. 

GEORGE  E.  MORROW,  A.M.,  Champaign,  Professor  of  Agriculture,  President. 
E.  E.  CHESTER,  Champaign,  of  State  Board  of  Agriculture. 

R.  T.  FRY,  Olney,  of  State  Horticultural  Society. 
H.  B.  CURLER,  DeKalb,  of  State  Dairymen's  Association. 

N.  B.  MORRISON,  Odin,  Trustee  of  the  University. 

ISAAC  S.  RAYMOND,  Sidney,  Trustee  of  the  University. 

THOMAS  J.  BURRILL,  PH.D.,  Urbana,  Professor  of  Botany  and  Horticulture. 

STEPHEN  A.  FORBES,  PH.D.,  Urbana,  Professor  of  Zoology. 
EDWARD  H.  FARRINGTON,  M.S.,  Champaign,  Chemist  of  Station. 

THE  STATION  STAFF. 

GEORGE  E.  MORROW,  A.M.,  Agriculturist,  President  of  Board  of  Direction. 

WILLIAM  L.  PILLSBURY,  A.M.,  Champaign,  Secretary. 
THOMAS  J.  BURRILL,  PH.D.,  Horticulturist  and  Botanist. 

EDWARD  H.  FARRINGTON,  M.S.,  Chemist. 
STEPHEN  A.  FORBES,  PH.D.,  Consulting  Entomologist. 

DONALD  McINTOSH,  V.S.,  Consulting  Veterinarian. 

GEORGE  W.  McCLUER,  B.S.,  Assistant  Horticulturist. 

GEORGE  P.  CLINTON,  B.S.,  Assistant  Botanist. 

WILL  A.  POWERS,  B.S.,  Assistant  Chemist. 
FRANK  D.  GARDNER,  B.S.,  Assistant  Agriculturist. 


UNIVERSITY  OF  ILLINOIS-URBANA 

Q.630.7IL6B  C002 

BULLETIN.  URBANA 
17-361891-94 


30112019529053 


